Ch2+MontantiJ

Jessica Montanti's Wikilog - Pd 6 CP Physics -Mrs. Burns - 2010 toc
 * Chapter 2**

= Section 1 =

sports and physics: The article, the Physics of Swimming by Karen C. Fox was featured in the Discover Magazine. Physicists and biologists researched why dolphins are able to swim so fast meanwhile their bodies to do not support them. After research it was established although the water is very dense and they do not have a lot of muscle they are able to swim very fast due to their shape. When compared to humans it was concluded we have a disadvantage in the sport of swimming due to our figure. - source: http://discovermagazine.com/2006/feb/physics-swimming

What do you see? one kid is running very quickly, the kid with a running start kicked the ball farther than the kid who was standing still. a mouse and lady bug are trying to push the ball.

What do you think? every sport includes moving objects or people or both. that is what makes sports entertaining. how do figures skates keep moving across teh ice at high speeds for long times while seeming to expend no effort? why does a soccer ball continue to roll across the field after it has been kicked? - you need strength to cause and object to move. the skates are small so in the ice skaters case it takes less to push off of. - the more momentum you have the farther the ball will go. once an object is in motion there must be an opposite force acting upon it to stop it.

Investigation X1: 1 c. 4.45 1 e. 4.45 2 a. he will go to the same point 2 b. because he is starting from the same point. 3 a. My prediction was correct because he kept going to the same height each time. 4 a. I think the skater will go higher on the slide I lowered because when he gets down the higher slope he gains more momentum causing him to go over the lower slope. 4 b.My predictions were correct because the skater traveled off of the track due to the fact that it was significantly lowered. 5 a. No because the line is vertical and the ramp does not go back up in height. 5 b. I think the skater would roll far because he would have a lot of momentum and only a small slope to travel up. 5 c. It would roll until something else acts upon it and would keep its momentum, which would keep it rolling. 5 d. It will travel on the track for forever. 6 a. The length will be increasing. 6 b. The height that it reaches is the same as the height that it started at regardless of the slope. 6 c. Both of the heights will be equal. 6 d. It would never stop and travel for forever.

Physics Talk pg 134-138 - Galileo changed how people thought objects moved. - Newton fist law of motion: in the absence of an unbalanced force an object at rest remains at rest, and an object already in motion remains in motion with constant speed in a straight line path. - an objects mass is a measure of its inertia, or tendency to resist a change in motion. - inertia is a property of matter. it measures the resistance to changes in an objects motion. - MASS is how we measure inertia. - kilograms is the base unit in physics. - mass: how much something has, how we measure intertia - weight: how much gravity is pulling on mass - velocity equations can show the different speeds involved. - speed is always relative to something - frame of reference: a vantage point with respect to which position and motion may be described - velocity: speed with direction - acceleration is how fast your speed is changing.

Checking up Questions p 138 1. intertia is a property of matter and measuring the resistance to changes in motion. 2. Newtons first law of motion says that if there is an object at rest is will stay in rest if no other force is exerted. It also says that an object that is in motion will remain in motion in a straight path. things wont change their motion unless they are forced to do so. 3. an opposite force. 4. the motion of a ball would be stopped by friction. 5. a larger object would have more inertia because it would be harder to stop, where as the smaller object would be easier to stop. 6. the ball will move because the train is moving. the placement of the ball must be determined before the train starts moving.

PTG #1-4 p 143 1 a) infinity because there is no unbalanced force to stop it. b) it will continue to travel for forever because newtons first law of motion states that if there is an object already in motion it will remain in motion with constant speed on a straight line if there is an absence of an unbalanced force. 2) 20 cm, it will reach back to what its original height was. 3) No, because everything has friction this would not be possible. 4) the puck is traveling at a very fast speed after it is hit until another force acts upon it, the other force is the friction of the hockey stick stopping the puck. Because in this scenario the puck has not hit the stick yet it would still be traveling at the very fast speed. its motion can be changed by hitting the puck against a wall or surface. 5) 7 m/s =2.5+4.5 6) 14.5 m/s =4.2+10.3 7 a) 8 m/s =5.6+2.4 b) 3.2 m/s -5.6-2.4 c) 61 m/s at 67 a2+b2+=c2 = 5.62+2.42 <--take the sq root = 6.1 8) 67 m/s = 85-18 9) a) 21.2 cm =45/sin(15) b) 43.9 cm =20/sin(15) c) 58 cm = 15/sin(15) d) 172 cm = 5/sin(15) 10)a) baseball: the glove stays at rest, while the is stopped when it is caught inside the players glove, when the ball is missed then it keeps traveling. lacrosse: the lacrosse stick stays in motion and catches the lacrosse ball in the net. if the ball is missed it will keep traveling. javelin: once the ball is thrown it keeps going until there is enough friction to make it stop b) - The player has missed the ball and now the hitter will have a homerun because of newtons first law of motion it will keep going! - the two teams now must race after the lacrosse ball that is traveling at constant speed since it missed the pocket of the offenders stick. - the javelin ball will keep rolling! it has broken a record and will keep making progress until friction acts upon it.

What do you think now? - it will eventually stop unless a different object acts upon the skate or ball. - the harder the original force was that moved the object was is the faster the object will move. - Momentum is used to gain speed on ice and continue to travel on the ice until another object such as friction acts upon in according to newtons first law of motion. - the soccer ball will stay in motion and continue to travel straight because of inertia unless an object acts upon it due to newtons first law of motion.

Inquiring Further 1 1) Curling shows Newtons first Law if motion because it exhibits friction. In curling the object that was thrown travels in a straight line motion until it is interrupted by another force or object. This analogy is not a perfect indication of friction because there is a little friction on the ice which slows the object being thrown down. source: physics of curling http://scienceblogs.com/builtonfacts/2010/02/the_physics_of_curling.php

Find and record three sports where there is motion with constant speed, and record when this motion takes place in that sport - bowling: the lack of friction down the path causes the bowling ball after it is thrown to have a constant speed - soccer: when a player kicks a ball for a penalty kick it has a constant speed until it is stopped by another player. - curling: after the object is tossed on the ice it has a constant speed until it is interrupted by another object.

=Section 2 = What do you see? in the top picture the boy is slowly walking home from school at a constant speed, while in the second picture the boy is running in a rush with flowers at constant speed in a hurry.

What do you think? 100 mi/h means that if the ball was traveling for 1 hour it would travel at a speed of 100. 45m/s means that if the ball was only traveling for 1 second it would travel at a speed of 45.

physics talk: - average speed: distance traveled/time elapsed: final velocity -initial velocity / time - instantaneous speed: the speed at the moment - acceleration: change in speed, change in time or elapsed time. - units for acceleration are meters per second squared - acceleration: change in velocity/change in time - velocities accepted units: m/s, km/h, mi./h - accelerations accepted unit: m/s^2

checking up questions p151 1) a) constant speed: they are all the same distance apart b) positive acceleration: start out closer and then gradually start to spread farther and farther apart. c) negative acceleration start out farther apart and gradually become closer and closer to together, more compact. 2) 8 mph 400/50 3) nstantaneous speed is the speed at the moment, while average speed is the distance traveled over the time elapsed. 4) 10 m/s^2 100/10

- when the signs of v and a are opposite, decreasing speed. - when the signs of v and a are the same there is increasing speed.

Answer Physics to Go (PTG) #1 - 4, 6 - 11, p154 - 156 1) Instantaneous speed is the current speed at that moment, while average speed the average velocity that was covered through out the whole time moving. 2) a) 1/15 = 66.7 mph b) 84/6 = 14 mph c) 9.6/2= 4.8 mph d) 400/4.5= 89 mph 3) a) negative acceleration (slowing down) b) positive acceleration ( speed up) c) zero d) negative e) zero f) zero 4) a) a constant increase in speeds a and d b) a constant speed b c) a greatest change in speed is a d) a increase then a decrease for c e) acceleration of a: positive constant, b: no acceleration, c: increasing then decreasing, d: constant positive acceleration a+ b 0 c + then - d + 6) a) 45(1000)/3600 12.5/9= -1.5m/s^2 7) a) constant  b) increasing acceleration c) slow constant --> decreasing --> slow constant d) increasing, constant, increasing 8) 100/2 = 50mi/hr 9) no this means that the average speed of his trip was 15 mph he could have traveled at 15 mph the trip of he could have traveled above that speed and below that speed to get the average. 10) .. . . . . . . . . . . accelerating -- constant  11) 1s:4 mph, 2s:8 mph, 3s:12 mph, 4s:16 mph 20 m/s 14) a) constant motion at an average speed: football when the ball is thrown b) constant motion at a fast speed: running for a soccer ball c) constant motion at a slow speed: a soccer ball when a goalie goes to pick it up d) positive acceleration: long distance swim meet, you must keep a steady pace at the beginning and then towards the end must increase your speed e) negative acceleration: learning how to jump hurtles you must slow down before you can practice jumping.

Physics Plus X2 - rebounding: when you change direction - even if the speeds are small the acceleration can be huge if the bounce times are tiny. 3) 5 b) 5 c) 5
 * velocity || acceleration || example ||
 * small || small || turtle ||
 * big || big || racecar, airplane, rocket ||
 * small || big || rabbit, dog, deer
 * (rebounding any object) ||
 * big || small || truck ||

What do you think now? 100 mi/h and 45 m/s both measure velocity and distance in relation to time. They are both examples of average speeds and instantaneous speeds because Velocity is found by dividing the distance traveled by the time.

= SECTION 3 =

What do you see? There is a girl pushing a ball with a stick. She starts out slow and then increases her speed. The dog at the bottom is following the same pattern as the girl.

What do you think? What is a force: a force is either a push or a pull How will the same amount of force affect a tennis ball and a bowling ball differently? Because the bowling ball is much heavier it has a greater mass and will need a stronger force to be pushed. The tennis ball is smaller and lighter and does not need as strong of a force to move it. the same amount of force will will make a tennis ball go farther than a bowling ball.

//Physics Talk// - newtons second law of motion= acceleration=force/ mass - a: f/m or f:ma or m:f/a - a is expressed in m/s^2, f expressed in newtons (N), m expressed in kilograms (kg) - all nonzero #s are considered to be significant figures and may of may not be significant, depending on their place in a number - zero between nonzero digits + - zero at the end of a decimal # + - zero at the beginning of a decimal - - in a large # w/o decimal points, the zeros - - when adding or subtracting the final result should have same number of decimal paces as the measurement with the fewest decimal places. - when multiplying and dividing the result should have the same # of decimal places as the measurement with the fewest decimal places. - weight is the vertical donward force exerted on a mass as a result of gravity. - equation: Fgravity = (m)(Agravity) ; W = mg

Checking Up questions, p167 #1-2. 1) newtons second law of motion is the force divided by the mass which gives you the acceleratio 2) increasing an objects mass would affect its acceleration by needing a stronger force to make the object move. In this case the acceleration would be smaller. 3) If the object is 30N then the force is 30N 4) Your weight would increase, while your mass would remain the same if you were on a planet with higher acceleration.

PTG 1) a) 350N, b) 80 kg, c) 10 m/s^2, d) 80 kg, e) -15 m/s^2, f. -3000

3) F = (m)(a) ; 42N = (.30kg)(a); a = 140 (m/s)/s 4) F = (m)(a) ; F = (.040kg)(20m/s^2) ; F = .8N 5) a) Newton's first law of motion A bowling ball has a larger mass than a baseball has. Meaning it has more inertia. A greater force would have to throw the bowling ball fast and hard enough so it continues at fast speed. The baseball has less inertia but will travel in straight-line motion for longer. The baseball will also be easier to accelerate. b) Newton's second law of motion, In the equation: F=ma the mass and acceleration are indirectly proportional. The baseball has less mass than the bowling ball and will have a larger acceleration and will be going faster when it makes contact with your hand. the bowling ball will not hurt your hand because it is going slower, but the baseball may hurt. 9) The force and power from your hand after you throw a ball stays upon the ball until a different unbalanced force makes contact. 10) 50N + 40N = 90N --> the unbalanced force is friction. If no friction was present then you will need very little force to push the desk. The friction makes it harder to push the desk, force must be applied. 11) The total force is four times 200 hundred which gives you 800 N, this is what you need to get the car out of the mud.........200 x 4 = 800 N 12) F=am 125N =a(.7kg) 178.57 --> 179 m/s^2 13) R= 130 N at 67 NE 14) 6403 N at 39 15) F=mg= F=(12.8kg)(9.8m/s^2) F= 125 N 16) a) 50 N at 53 b) 8.9 m/s ^2 17) a) 36 N b) .36 m/s^2 c) .5 m/s^2 18) The goalie is getting ready to kick the goal kick. He is extending his right leg backward to get more acceleration on the soccer ball that is .43 kg. The harder he hits the ball the farther it will travel because he will have a greater acceleration.....The goalie hits the ball at a speed of 25 m/s leaving the players foot and sending it down the field. source: http://hypertextbook.com/facts/2002/LouiseHuang.shtml work :





What do you think now? - Force: a push or a pull - Mass and acceleration are indirectly proportional. - if the mass is increased then the acceleration will be less....vice versa - more mass --> more interia - if they both have the same force, but the bowling ball has a larger mass then it would have a smaller acceleration. the baseball has a smaller mass which means it would have a greater acceleration.

Physics Plus =Section 4=

What do you see? - A girl is standing on a latter and throwing down both green and red apples. The red apples are thrown straight down and the green apples have a projectile towards the right. The boy with two heads to keeping track of the times taken to reach the ground by the different apple colors and recording their speeds. The apples are evenly placed horizontally.

What do you think? How far an object travels is determined by the amount of strength and force is placed on the object when it is launched, the angle it is thrown at, the height it is thrown at, the weight of the object, velocity.

Physics talk - trajectory: path...term used for projectiles - projectile: an object acted upon only by gravity. (something is not a projectile if there is air resistance) - The x component and y component of all vectors are independent --> only effected by others...x components are only affected by x components (same for y components) vertical distances are only effected by vertical distances - y: vertical and x: horizontal - Time for a horizontally launched projectile to reach the ground (hang time) is the same as the time it takes to drop. - acceleration due to gravity is 9.8 m/s^2 - vertical velocity changes by -10 m/s every second - vy: 0 at maximum height - throwing horizontally results in the same trajectory as the second half of the path of a ball thrown at an angle.

Investigate 4 Part C

1. As the horizontal launch velocity increased, the hang time stayed the same. 2. As the launch velocity increased, the range increased 3. As the initial height increased, the time in the air increased 4. As the initial heigh increased, the range increased 5. Factors that influence the time of flight: initial height. The greater the height the more time. 6. Factors that influence the range: initial height and the initial speed

Checking up 1. if a pen and a ruler are dropped together from the same height, will they reach the ground at the same time? Explain your answer. Yes, they will hit the floor at the same time as long as there is no air resistance because the mass of the objects is irrelevant. Acceleration is acting upon both at the same rate 2. When an object falls vertically down, does its velocity remain the same? Explain your answer No, it accelerates about 10 m/s every second. 3. If a ball is thrown upward, what is the balls velocity at its point of highest rise? What is the balls acceleration? the acceleration is -9.8 m/s^2 and the highest point of rise is 0.

PTG 4) My friends thought that the bullet going vertically down would reach the ground first, however they are incorrect because they would both reach at the same time. I think people easily believe coins hit at the same time, but not bullets because most people assume that because the bullet is sent outwards it will take longer. The vertical part is what is the same not the horizontal. 6) This statement is true because x components and y components of all vectors are independent. For example, vertical distances are only effected by vertical distances and vice versa for horizontal. 7) They will both his the ground at the same time. The versicle part is the same while the horizontal is not. 8) 36 at 33.7 9) a) 11.98 m/s b) v=d/t 11.3= d/t d= 23.96 m 10. a) 8.5 m/s b) 4.25 11. The first pitch was swiftly chucked from the pitchers hand. It was sent directly to home plate at 60 m/s. The batter sent a line drive to first base at an angle of 30 degrees and the player on the base caught the ball and the batter was just struck out! work:

Video & Questions [] 1. Projectile motion occurs in volleyball when a player servers the ball to the other side of the quart. The higher the ball is hit the farther it will travel. Change only occurs in the vertical direction because the volleyball must be hit hard and fast enough that it makes it over the net and onto the other side. As the ball goes up, it may loose velocity, however it the sends the ball to the other side of the quart. Without air resistance there is not a horizontal change, so it will continue to move in the direction that the person was moving which is why in volleyball it is very important to follow through with your arm swing to direct the ball in the right direction. Horizontal is how far forward the ball was going to travel, while vertical is how high up the ball was going to travel. 2. The shape of the trajectory is important because it shows the course that the volleyball will take. Once you serve the ball it continues forward in an upward potion and then declines down. In volleyball the horizontal motion is constant, while vertical motion is uniformly accelerated when the ball is served correctly.

pg 180 physics plus

What do you think now? What determines how far an object thrown into the air travels before landing? launch velocity What do you think determines how far an object travels after it is thrown? initial height and the initial speed - When the initial height is changed (increased or decreased) and the launch velocity is changed (increased or decreased) it determines how far the object is going to go while it is in the air.

=SECTION 5=

What do you see? A girl kicked a ball and hit another person in the head. The ball then bounced from his head and into the goal.

What do you think? Describe the trajectories of projectiles launched from the ground at various angles. Describe how a greater launch speed of a projectile might change the range when the launch angle is the same. - complementary angles have the same range for ground to ground launch. (45 has maximum) - If you launch it faster it is going to go further.

Physics Talk - a projectile has two motions that act at the same time and do not affect one another (this is from section 4) - without air resistance the path of all trajectories are parabolas (bowl-shaped curves) - when you throw a ball it follows a parabola. - air resistance makes trajectories more complex. - the temperature of the air affects the distance a ball will travel. - Angle, Speed, Height and range also have to do with projectiles - baseballs and golf balls do not follow true parabolic paths. (baseballs can curve if the pitcher puts a certain type of spin on the ball.)

Physics Plus

Checking Up 1) constant and downward acceleration. 2) it must match reality in nature. 3) A 45 degree launch produces the greatest range. When pairs of angles add up to 90 degrees, distances will become identical. When going from 10 to 80, horizontal height and range increase.

PTG 1) 45, this will cover the most ground 2) a) more b) less 3) a) 90-30: 60 degrees b) 90-15= 75 degrees 4) Vix > Viy< 45 it is almost impossible 5)vox high + his dy max is HIGH He made sure to have a fast initial velocity and a certain angle when he jumped to ensure a great distance. 6) a) a=-g=-9.8 m/s^2 down b) Vmax: Vix only because Vy= 0 at max height 7) a) V= Vi +at -9.8 x 3 = 29.4 m/s Vertical speed final: 29.4 m/s 7) b) horizontal speed after 1 second: 5m/s 5:VIT vi:5.0 7) c) 15 m from the cliff d:vit d:15cm 8) 45 degrees creates the longest range 9) the largest angle 10) a) direction of acceleration: down 10) b) -100 : .5 x -9.8 x t^2 t = 4.5 seconds to reach the ground 10) c) d : vit+1/2 at^2 d: 20 (4.5) d: 90 meters from the base of the cliff.

problems:

what do you think now? 45 degrees gives you the largest range. It is larger than 45 degrees there will be more air time, but a smaller range. - Complementary angles add up to 90 degrees. - when two numbers add up to 90 then they have the same range.

= **Section 6** =

What do you see? There is a boy who is sitting on a wheely chair with his feet leaning against the wall. When the boy pushes his feet off the wall he is sent back with the chair still sitting in it.

What do you think? If instructing someone how to jump I would have them first keep their feet on the floor and then instruct them to bend their knees in order to get enough power. I would then have them push off the bottom on their feet upward.

Physics Talks - newtons third law of motion: for every applied force, there is an equal and opposite force. The two forces always act on different objects. - force always comes in equal and opposite pairs. ex: if you push on the wall, the wall pushes on you with the same force. - free body diagram: a diagram that shows the force acting on an object. It is used to show the relative length and direction of all forces acting on an object in a given situation. - center of mass: the point at which all the mass of an object is considered o be concentrated. how newton described the third law of motion: - for every force applied to object a by another object b, there is an equal and opposite force applied to object b by object a. - if you push or pull on something that something pushes of pulls back on you with an equal amount of force in the opposite direction. this is an inescapable fact- it happens every time. - forces always come in pairs. - newtons three laws of motion 1. things wont change motion unless forced to do so. 2. a= f/m 3. all forces come in pairs, but act on two different systems.

Checking up 1. Newtons third law of motion says that for every applied force there is another force that is equal and opposite and they both always act on different objects. All forces come in pairs, but act on two different systems. 2. the mass pulling up earth with an equal force of gravity. 3. free body diagrams illustrate the force acting on an object. It is used to show the relative length and direction of all forces acting on an object in a given situation.

Answer PTG #1-8 1. When an athlete is preparing to throw a shot put, the force on the athletes hand is equal to the opposite force because they are always equal, just in different directions. 2. No because when weight is put on the chair the pressure or spring causes the chair to go down. "restoring" forces balance downward weight. 3. the more weight put on the scale the spring is hit and the spring is attached to a needle and they calibrate to make the number on the scale higher or lower. (this is like the scale at the dr office) your weight (the normal force) is equal to the normal force that the scale puts on you. 4. the forces are equal but opposite because and the bat would break because the material cannot withstand that force. 5. The force on each athlete is equal but opposite however the big line backer has a larger weight this a smaller acceleration than the smaller player. they will both experience the same force. 6. equals forces but opposite F boards on player = - F player on boards 7. the padding of the gloves causes a lower acceleration of the ball which reduces the force on the hand. when you move back with it you reduce the force, the bigger the distance you are going to take to slow it down the less the acceleration will be. 8. a) The large 6 ft 6 volleyball player jumps into the back row 5 foot 5 small player and the taller player exerts more exert the same amount of force except they are opposite. This description would be made more exciting if a real video was added to it. b) when a mass (weight) is pushed to the floor it produces an opposite force. this would be made more exciting if there was a video showing an example of it.

What do you think now? I would have them first keep their feet on the floor and exert a force on the floor I would then have them push off the bottom on their feet upward exerting their weight on the floor. Their force will be equal and opposite to the force of the floor.

= Section 7 =

What do you see? A girl is easily pulling a shoe on ice, but is having trouble moving the shoe in the sand. She is having trouble because there is friction on the sand and the ice is frictionless so it is easy to pull the shoe.

What do you think? When a sport is played on a surface that has little friction different shoes are needed than for a sport that is played on a ground with a lot of friction. For example you need different shoes for playing soccer outside on turf than for indoor soccer that is played on a shiny frequently polished gym wood floor.

Physics Talk - the coefficient of sliding friction (mew, a u with a tail in the front) is defined by the ratio if the force of friction/normal force (perpendicular force exerted by the surface on the object) = Ff-Fn - the force of friction is equal to the force required to slide the object on the surface with a constant speed. - µ does not have any units because it is a force divided by a force; so they cancel each other out. - µ is usually expressed in decimal form.

Checking up

1. the force of friction and the force on the spring scale are equal because the friction force and force applied when pulling was equal. They are equal but opposite. 2. it has no units because it is force (newtons)/ force # 2 (newtons) 3. the force of friction is equal to the force required to slide the object this is the constant speed.

PTG

1. in track a change in weather condition such as rain would cause the runner to want more friction so they would not slip while running. the runnner may want to wear different shoes that are a little heavier when running in the rain so they can gain traction. ex: length of cleats 2. ice hockey is a sport that requires little friction because ice is a frictionless surface. In order to keep the friction down the players usually clean their skates before skating and play on freshly groomed ice rinks. ex: skiers wax skies and ice skaters sharpen skates 3. She is going to need to know what the floor of the court is made out of, however this is not true because all surfaces have a different amount of friction. 4. Tennis players need different shoes for different surfaces because some surfaces have more friction than other and therefore they would need different shoes to stay stable while playing. For example, because clay is a rough surface you dont need as much friction. 5. The minimum horizontal force would be 18 N .03 = / 600 N. 6. a) w: mg w: 1000 (9.8) w= 9800 N  b) µ=f/n .55: f/9800 5390 N: f c) FX:ma -f:ma -5390:1000a <span style="font-family: Arial,Helvetica,sans-serif;">a:-5.39 m/s^2 <span style="font-family: Arial,Helvetica,sans-serif;">FY: max <span style="font-family: Arial,Helvetica,sans-serif;">FY:0 <span style="font-family: Arial,Helvetica,sans-serif;">N-W=0 <span style="font-family: Arial,Helvetica,sans-serif;">N=W <span style="font-family: Arial,Helvetica,sans-serif;">d) vf= vi + at <span style="font-family: Arial,Helvetica,sans-serif;">0= vi + (-5.39) (6) <span style="font-family: Arial,Helvetica,sans-serif;">32.34 vi <span style="font-family: Arial,Helvetica,sans-serif;">e) he was not telling the truth about his speed of 29 m/s^2. if the speed limit was 65 he would have gotten a ticket. <span style="font-family: Arial,Helvetica,sans-serif;">7. Air and water resistance remains constant, however the speed changes. Air and water resistance depend on speed. When an item that is falling fro m the air the faster it is falling the more resistance it will have, when you walk slowly in water the force does not feel as big. 8. u:f/n Yes fk max limits accel. When there is a maximum force there is a limit put on how far something can be sent. There is a restriction on acceleration and the strength of your legs does not matter. You can reduce the friction by changing the surface to a less textured surface for example going from sand to ice.  9. An athlete shoe company would use our results by saying the shoes are not heavy and the lightest shoes around, there bottoms are thick so the players do not slide around on and have good traction while playing. 10. Friction is important to running because you need good traction to stay on the ground and not slip or fall. Cleats are used in football, soccer, and other sports because you need friction to keep the players feet on the turf and not slide. no friction = no walking 11. Reporting from the PHHS track about the relay race tournament. The PHHS runners are all wearing special running shoes that they say are lighter which allows them to gain friction and run faster.

__Physics Plus pg 215 number 1__

__ LAB: BOWLING WITH BLOCKS __

`Table 1 µ || % Difference || <span style="font-family: Arial,Helvetica,sans-serif;">WORK SHOWN for table 1 <span style="font-family: Arial,Helvetica,sans-serif;">- Ff <span style="font-family: Arial,Helvetica,sans-serif;">4 + 4.1 + 3.9 /3 = 4N µ:f/n <span style="font-family: Arial,Helvetica,sans-serif;"> -percent error <span style="font-family: Arial,Helvetica,sans-serif;"> (calc time-your time)/calc time X 100 = percent error <span style="font-family: Arial,Helvetica,sans-serif;"> I3.25-3.4I/3.25 X 100 <span style="font-family: Arial,Helvetica,sans-serif;"> - µ <span style="font-family: Arial,Helvetica,sans-serif;">µ : f/n : T/n : 4/11.8: .34
 * Tension (N) || Ff (N) || Total Weight (N) || µ || Class Average
 * 4.0/4.1/3.9 || 4 N || 11.8 N || .34 || .325 || 4.6% ||

Table 2 (g) || Mass (kg) || Measured Times (s) || Measured Distance (m) || Ff (N) || Acceleration (m/s^2) || Calculated vi (m/s) || Calculated times (s) || % error || __WORK SHOWN for table 2__ <span style="font-family: Arial,Helvetica,sans-serif;">Ff <span style="font-family: Arial,Helvetica,sans-serif;">µ:f/n <span style="font-family: Arial,Helvetica,sans-serif;">acceleration <span style="font-family: Arial,Helvetica,sans-serif;"> -Fy: may .54: .17a a: 3.17 <span style="font-family: Arial,Helvetica,sans-serif;"> - Fy: may Fy: 0 N-W:0 N:W (.17) (9.8) W: 1.66 N <span style="font-family: Arial,Helvetica,sans-serif;"> - .34: F/ (9.8)(.17) <span style="font-family: Arial,Helvetica,sans-serif;">calculated vi <span style="font-family: Arial,Helvetica,sans-serif;"> - vf^2: vi^2 + 2ad 0: vi^2 + 2 (3.17)(3.3): 4.57 <span style="font-family: Arial,Helvetica,sans-serif;"> 0: vi^2 + 2 (3.17)(4.2): 5.16 <span style="font-family: Arial,Helvetica,sans-serif;"> 0: vi^2 + 2 (3.17)(6.65): 6.5 <span style="font-family: Arial,Helvetica,sans-serif;">calculated times <span style="font-family: Arial,Helvetica,sans-serif;"> - vi^2 = vi^2 + at vi/a: 4.57/3.17 : 1.44 5.16/3.17: 1.62 6.5/3.7: 2.05 <span style="font-family: Arial,Helvetica,sans-serif;">percent error - (calc time-your time)/calc time X 100 = percent error
 * Mass
 * 177.93 || .17 || 1.33 || 3.3 || .54 || -3.17 || 4.57 || 1.44 || 7.63% ||
 * ||  || 1.39 || 4.2 || .54 || -3.17 || 5.16 || 1.62 || 14.2% ||
 * ||  || 2.18 || 6.65 || .54 || -3.17 || 6.5 || 2.05 || 6.34% ||

Questions 1. The coefficient of friction in part I is the friction/ forces going against each other between the block and the surface on the bottom. 2. My mu was .34 and the class mu was .325 they are .015 different with a 4.6% difference. The results can vary because of random errors or systematic errors. 3. My times agreed and my percent errors were all lower than 15%. The highest was 14.2% and the smallest was 6.34, I think they are pretty accurate. Some of mine were high while other were low. 4. The theoretical physics were are doing in class applies to the real world in many ways. For example, in some sports we play this newton law applies. For example, bowling contains coefficient of friction. 5. 1. slippery floor the block would travel farther. 2. if the surface has bumps it can throw off the acceleration. 3. if the stop watch is not stopped/started precisely the calculations would be thrown off by a little. 4. if it is not measured correctly on the meter stick there can be an error.

What do you think now? Why do some sports require special shoes? Some sports require special shoes because the surface they are played on either needs a lot of friction or less friction to be played right and safely.

Why would different features of a shoe be useful for different sports? Different shoes are useful for different sports because every sport needs a different amount of friction because of the surface it is performed on. For example, for figure skating the skater would need ice skates on the frictionless ice and for something like basketball the player would need shoes with friction to keep them steady. The more friction there is the harder it is to slide so a basketball player would want to wear shoes that exert a lot of friction so they do not slide, while a figure skater would not want this.

=Section 8=

What do you see? The people are pole vaulting and trying to make it up to the top of the building. The volt converts horizontal motion into vertical motion and helps the acceleration. There is a lot of speed that changes into height.

What do you think? - The 11. m long pole is not long enough on contrast to the bar compared to the 5.5 pole at the 6 m height. - Factors that limit the height a pole vaulter can attain are the speed they are traveling, the height of the surface they are trying to get over,

Investigate 8: less the ruler sticks out Pre lab Activity a. the smaller amount of ruler that is hanging off the table allows for a greater height of the penny. b. the more ruler the smaller the height, the less ruler the higher the height. The position of the penny also affected it, the farther off the penny (closer it is to the end) the greater the height will be. The flexibility of the ruler and how far off the ground the ruler is also affects the height. Instructions: a. how the penny changes when it amount of ruler sticking out changes. b. the height of the penny when the distance changes. c. meter stick, ruler, penny, table, tape d. by keeping track of the height of the penny when the rulers position changes. Data Chart: length of ruler I height of penny ruler: Conclusion: The penny will go the highest when about half of the ruler is hanging off the table and half of it still on the table.
 * = 5 cm ||= 14 cm ||
 * = 10 cm ||= 158 cm ||
 * = 15 cm ||= 120 cm ||
 * = 20 cm ||= 112 cm ||
 * = 25 cm ||= 95 cm ||
 * = 30.5 cm ||= 8 cm ||

Physics Talk - Kinetic energy: energy something has because of motion - gravitational potential energy: energy something has due to its location relative to the ground - Elastic Potential Energy: energy a spring has when stretched or compressed. - when forces act on objects, energy changes from one form to another but the sum of KE and PE remains constant. 1/2kx^2 - Work = F x d - the concept of total energy remains constants is referred to as the law of conservation of matter. - Joule = 1 N x m = 1 (kg x m^2 / s^2) - Law of Conservation of energy: energy cannot be created or destroyed; it can be transformed from one form to another, but the total amount of energy remains constant

Law of Conservation of energy: energy of a system remains constant although the types of energy might change. Energy can be transferred from one type to another. The only way to increase or decrease the total energy is being doing work. Initial Energy + Work Done on System = Final Energy + Work Done by System


 * type || def || equation ||
 * Kinetic || energy something has because it is moving || KE=1/2 mv^2 ||
 * Elastic Potential || the energy is spring as when it is stretched or compressed || EPE= 1/2 kx^2 ||
 * Gravitational Potential || energy something has due to its location relative to the ground. || GPE= mgh ||
 * Work || is caused when a force is exerted over some distance parallel to the motion || w=Fd ||

1. Force causes it to change. 2. From elastic potential energy when the ruler is bent. 3. The vaulter's kinetic energy is used to give the initial speed upward, and the rest of the kinetic energy is turned into elastic potential energy as the pole bends in.
 * Checking Up.
 * Checking Up.

PTG 1. At first the throwing of the shot-put is work, then kinetic when it is being thrown, but when ball reaches max height it goes to gravitational W --> KE --> GPE --> KE --> W

2. At first the golfball stays at rest once it is hit by the club work takes place. When the ball is hit its kinetic energy is increased and as it travels up there is gravitational energy. When the ball is going back down there is kinetic energy because it is moving. When the ball stops at the ground there is work.

3. KE = GPE 1/2mv^2 = mgh 1/2(12)^2 = 9.8h 7.3m:h

4. There are other factors that need to be taken into consideration such as the speed of the athlete. The length if the pole is not the limiting issue

5. The poles temperature would increase when the vaulter does work because its kinetic and then elastic energy. The pole will decrease its temp when the vaulter increases the gravitational potential energy.

6. KEi=GPE 1/2mv^2=mgh 1/2v^2=9.8 (4.55) v: I2(9.8)(4.55) v = 9.44

7. KE = GPE 1/2mv^2 = mgh 1/2v^2 = (9.8)6.14 v=10.97 m/s Sergi's speeds higher

8. a. GPE=KE mgh = 1/2mv^2 (9.8)(100) = 1/2v v = 1960 m/s b. they cancel so you dont see the mass of the rock

9. a. W pull back = EPE f 1/2kx^2 = 1/2 (1500)(.25)^2 46.875 = W b. EPE= KE 1/2kx^2= 1/2m^2 1/2(1500)(.25)^2 =1/2(.1)v^2 30.6 m/s = V

10. a. EPE=W 1/2kx^2=f(d) 1/2 (315)(.3)^2 = W 14.2:W b. 14.2=F(.3) 47.3 N:F

11. GPE=EPE mgh= 1/2kx^2 .04(9.8)(1)=1/2(18)x^2 x = .21

12. F=ma N= kg (m/s^2) W= F(d) J = N(m) GPE =mgh = kg(m/s^2) (m) = N(m) =J KE=1/2mv^2 =kg (m/s^2) = kg (m^2/s^2) (m) = N(m) = J GPE: 1/2kx^2 = N/ (m^2) = N(m) = J

13. EPE --> KE --> GPE --> KE

14. At first the push is work, then kinetic but when ball reaches max height it goes to gravitational W --> KE --> GPE

What do you think now? - It is the speed that matters not the length of the pole because the more velocity the higher the kinetic energy and the higher the kinetic energy the more gravitational. The amount of energy put in the beginning is the same amount of potential energy you are going to have at the end, because the energy is changing from one type to another because of the law of conservation of energy.

- The speed they can run at, their height, and the stretchiness of the pole limits the height a pole vaulter can attain.

=Section 9=

What do you see? A girl is in a helicopter timing the ice skaters hang time.

What do you think? World Class figure skaters do not defy gravity because they have proper training to do the triple axis.

Investigate 9 prelab activing 3. figure skater 20 frames (1/30s) = 2/3 second basketball player: 31 frames (1/30s) = 1 second 4. The changes and displacement are so small so it looks like he is not moving his legs much and hovering. Instructions 1. Process: a. bend your knees getting ready to jump --> W unbending legs b. then you unbend your knees and put your arms up --> gravity c. air born height off the floor W unbending legs = GPE final 2. a. the weight of the normal force b. the height of your jump and your own weight c. tools: meterstick, scale, tape d. we will have a graph with our findings and data. 5. My measurement was 1071.1 on data studio, but when I did the calculations myself i got 640.26.

calculations Fd=mgh F(.3)= 192.08 F= 640.26

percent error Icalc-experI/calc (100) 430.74/1071 (100) = 40.2 % ||

Physics Talk Conservation of Energy - when jumping: ready position has EPE from contractions in muscles, launch position has both GPE and KE. - Energy of all jump positions are equal - larger the peak position larger the GPE - every energy can be calculated of measured.

Checking Up 1. EPE because of the leg muscles that allow the jumper to move from the ready position to his launch position. 2. There is in the launch position GPE and KE and at the height of the jump there is GPE 3. chemical energy, light energy, sound energy

PTG 1.W in==GPE=mgh = 50(9.8)(1) = 490 J

2. Win +GPE --> KE --> W out (brake)

3. There is no such thing as hang time because people do not hover in the air. You could show people segments of a video of some playing a sport and frequently pause the video showing the change in the players body/

4. The person claiming the law of physics is not true should prove their idea because the person who believes it is true already has evidence that it is true. It is already accepted as a law so in-order to disprove it you must show evidence. There is a burden of truth for the person making the claim. The other person should try and verify the evidence found by the non believer.

5. increase force by getting stronger or decrease mass by loosing weight but not muscle mass rather fat mass.

6. - the amount of work done. a) 1(1) = 1J b) 10(1) = 10 J c) 10(1) = 10 J d) .10(100) = 10 J e) 100(.10) = 10 J

7. a) 1J b) 10 J c) 10 J  d) 10 J  e) 10 J

8. a) 1J b) 10 J  c) 10 J  d) 10 J  e) 10 J

9. F(d) 50 N (43 m) = 2150 J

10. (62)(8.2)(9.8) 2084

11. a=f/m 30/5 6m/s^2 b. f(d) = w 30(18.75) 563 J

12. a. d=w/f 40000/3200 12.5 m b. f/m=a 3200/1200 2.7 m/s^2

13. w=KE=1/2mv^2 =1/2 (150) 40^2 120 J

14. W= KE = 1/2mv^2 F (d) - 1/2mv^2 (417) (d) = 1/2 (64) (150^2) 7 m

15.
 * || KE || GPE || EPE || SUM ||
 * running || 100 J || 0 || 0 || 1000 J ||
 * full bending of the pole || 10 J || 0 || 90 || 100 ||
 * peak height || 0 || 100 || 0 || 100 ||
 * landing || 85 || 15 || 0 || 100 ||
 * cushion || 0 || 0 || 0 || 0 ||

16.
 * || KE || GPE || EPE || Sum ||
 * peak h || 0 || 1000 || 0 || 1000 J ||
 * landing || 800 || 200 || 0 || 1000 J ||
 * lowest h || 0 || 0 || 1000 || 1000 J ||

17.
 * || KE || GPE || EPE || Sum ||
 * top of mnt || 0 || 1000 || 0 || 1000 J ||
 * middle || 700 || 300 || 0 || 1000 J ||
 * bottom || 1000 || 0 || 0 || 1000 J ||

Physics Plus 1. a) GPE --> KE mgh = 1/2mv^2 196 = 1.2 v^2 v= 19.8 m/s v - 20 m/s b) the m's cancel because they are present in both the GPE equation and the KE equation. In a more practical stand point you say objects in free fall with fall at the same rate regardless of mass.

2 EPE + GPE = Kef. EPE ---> KE 1/2 k x^2 = 1/2 .3 v^2 9.6= .3v^2 32 m/s =v^2 5.7 m/s= v v= 4.2

3. GPE=KE 200(9.8)h=1/2(200) h=20 m

What do you think? No athletes do not defy gravity, because gravity effects everyone equally according to the law of conservation of matter. The figure skater is constantly moving while they are in the air even if it is very little and hard to see the skater is always moving.