Ch4+MontantiJ

Jessica Montanti's Wikilog - Pd 6 CP Physics -Ms. Burns - 2010 Chapter 4 - Thrills and Chills toc

=**Section 1**= What do you see? The girl is pushing the boy around in a wheeley chair while they are thinking about being on a roller-coaster. They are similar because they both have a change in direction and velocity. What do you think? The drop produces the greatest scream because your stomach drops and the the distance from the ground is so great.

hw 2/28/11 http://www.ultimaterollercoaster.com/resources/tv/topten/topten_list.shtml - The Comet at the Great Escape in Lake George NY, is famous because of design full of hills and drops that give the riders the sense of floating out of their seats in the air. - The Cyclone at Astroland in Brooklyn, NY is famous because when it was built in 1927 and broke records in speed, height, and fright. The ride is unparalleled 58.6 degree first-drop and its amazing speed of 60 miles per hour.

Physics Talk scalar- can be measured with flexible string it is a quantity that has magnitude (size/amount), but does not have any direction  speed- distance traveled divided by time elapsed. Speed is scalar it has no direction.  vector- has magnitude and direction  displacement- the difference in positions; it depends only on the endpoints, not on the path. vector  velocity- displacement divided by the time elapsed. Velocity is a vector it has a magnitude and direction. average velocity: displacement. time elapsed v: change in d/ change in t  acceleration- the change in velocity divided by the time elapsed. It is a vector and will be in the direction of the change in velocity. equation for acceleration: change in velocity/time elapsed. a: change in v/ change in t

Checking Up  1. Explain the difference between distance and displacement. Distance is scalar which means it has no direction while displacement is vector which means it does have direction.  2. You went to school and back home in a total distance of 2 km. What is your displacement? It would be 0.  3. What is the difference between speed and velocity? Speed is the distance and time and is a scalar meaning it has no direction while, velocity is displacement and time and a vector meaning it does have direction. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> 4. How can you find the acceleration of an object? equation for acceleration: change in velocity/time elapsed. a: change in v/ change in t

Do PTG #1-2, p 358 6-8 and 10 1

2. The biggest thrill would be on hill 1 because this is not only the biggest drop but the first drop. At the beginning of the ride the passengers will not expect the huge drop at the beginning and this will cause their stomachs to drop and excitement.

3. a. Bigger radius means higher speed, so La Paz, Bolivia would have a greater speed because it has a larger circumference. V: (2)(3.14)(R)/ T = 86400 b. v: change in d/ t 40000/24 1666.6 c. you dont feel any acceleration because it is going at such a high speed.

4. a: change in v/ t a: 16-4/ 3 12/3 a: 4 m/s

5.a. speed b. velocity c. vecloity d. displacement and velocity e. displacement - tells direction

6. A lab cart if 10 cm long, It travels through a velocimeter in 2 s. Calculate the carts speed. d: 10 t:2 d/t 1/2 s: .05 m/s

7. A second lab cart is 5 cm long. If it were traveling at the same speed as the cart in q6, what would the velocimeter record as the elapsed time? s: d/t 5: 5/t the velocimeter would read 1 second.

8. Your vehicle accelerates from 0 - 25 m/s (about 55 mi/h) in 10 s while traveling down a straight street. what is the acceleration of your vehicle? a: vf-vi/t 25/10 2.5 m/s62 = a

10. a. I would make the drops shorter and also changing the radius of the loop to be larger to make the loop more gradual.

What do you think now? the loudest screams will be produced when the ride is changing its direction at this point bodies will feel heavier as the roller coaster cart is changing its route.

=<span style="font-family: arial,helvetica,sans-serif;">**Section 2** =
 * What do you see? **
 * One cart is going down a very steep roller coaster while the other cart is on relatively flatter track. **

The roller coaster with the more steeper track will have a greater thrill because of the steep track
 * What do you think? **

Physics Talk p363-367 and answer checking up questions #1-5. <span style="border-collapse: separate; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">- GPE: mass X object X strength of gravitational field X height =mgh <span style="border-collapse: separate; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> - KE: energy an object has because of its speed <span style="border-collapse: separate; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> - GPE: mgh J <span style="border-collapse: separate; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> - KE: 1/2mv^2 J - mechanical energy: the sum of KE and GPE - GPE increases --> KE decreases, KE increases --> GPE decreases - the sum of the GPE and KE is constant (as long as friction is not important). GPE + KE = constant - Mechanical energy (bottom) = mechanical energy (top) - KE (bottom) + GPE (bottom) = KE (top) + GPE (top) ---> sum of those two must be the same at the top as it is at the bottom.

Checking Up 1. the larger the height is where the ball is released the greater the speed is going to be when it reaches the bottom. 2. When the height goes up so does the GPE, when the mass goes up so does the GPE....this works the same for decreasing. 3. When the speed increases so does the KE, when the mass increases KE does also......this works the same for decreasing. 4. Going down the hill the GPE decreases (less weight at this point) .....it becomes converted into KE energy which then increases because when going down the hill the speed increases which means the KE gets larger. 5. KE=1/2mv^2 It would have 30,000 J

PTG 1. Their speeds are the same at the bottom because their initial heights are the same even though the inclines are different.....as long as you are ignoring friction.

3.
 * ** position of cart (m) ** || GPE: mgh J || KE: 1/2mv^2 J || GPE + KE J ||
 * top || 60,000 || 0 || 60,000 ||
 * bottom || 0 || 60,000 || 60,000 ||
 * half || 30,000 || 30,000 || 60,000 ||
 * 3.4 || 15000 || 45000 || 60000 ||

4.

5.
 * mass: car --> height m || GPe || KE || GPE + KE ||
 * top || 60,000 ||~ 0 || 75,000 ||
 * bottom || 75000 || 75,000 || 75,000 ||
 * half || 375000 || 37500 || 75,000 ||
 * 3.4 || 15000 || 60000 || 75,000 ||

6.

7. a. GPE:mgh .2(9.8)(.75) 1.47 J b. KE:GPE mgh:1/2mv^2 (9.8)(.75):(1/2)(v^2) :3.83 m/s c. half way because it will be split GPE:KE mgh:1/2mv^2 9.8h:1/2x3.83^2 :.75 m

8. The speed will remain the same whether are 6 or 26 passengers because it is independent from the cars mass since the masses cancel in the equation.GPE:KE all through out the ride.

9. a. At point B because it is coming from a steepest height b. C & F because they are at the same height/ c. D because it is coming from an incline while E is on top of a hill.

10. The height of H is much higher than the GPE so the roller coasters cart will not be able to reach point H. When the GPE converts to KE it will be able to get up the hill but not to the top because in total there is not enough energy.

11.
 * <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">Position || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">Height m || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">GPE:mgh J || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">KE:1/2mv^2 j || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">GPE+KE J ||
 * <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">bottom of hill || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">0 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">0 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 ||
 * <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">top of hill || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">25 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">0 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 ||
 * <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">top of loop || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">15 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">30000 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">20000 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 ||
 * <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">horizontal loop || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">0 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">0 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 || <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">50000 ||

What do you think? They would be the same because they both have the same height. The length of the track doesn't matter only the height does. The carts will have the same velocity on the way down because heights are the same.

= **Section 3** =

What do you see? Students are measuring how high a pop up toy goes. The toy has a spring and they students are calculating the SPE, KE, and GPE ad measuring the height with a meter stick and time with a photo gate timer.

What do you think? Roller coasters get up to their highest point by being pulled up to the top and then increasing their speed down. They can only go as high as they went up before. When the roller coaster cart has more people the ride requires more force.

Physics Talk - spring potential energy (EPE) is with a spring when its compressed or stretched. - energy is never lost....it can be changed into a difft kind of energy (heat & sound energy)....total amount of joules (J) always remains the same - Thermal energy: work due to friction -- friction creates heat -- thermal energy - EPE= 1/2 kx^2 k: spring constant x: the stretch or compression

Checking up Questions 1. The spring potential energy turns into KE and GPE when it bounces off the table conserving all the energy. 2. 2 J of KE when it leaves the table 3. 2 J of GPE at the top 4. The two factors are the spring constant & the distance it either being stretched or compressed.

PTG <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">5. The KE=GPE, therefore the second cant be higher because the roller coaster is not going to have enough KE to make it up the for the second time.

<span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 6. There is friction is a force that creates work which takes away from the other forms of energy making less available to make KE or GPE. It stops the carts and roller coaster systems have breaks and are designed in a way that creates a part to slow down and stop the ride.

<span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 7. GPE <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> (300)(9.8)(15) <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 44100 J

<span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 8. a. KE: 1/2mv^2 <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">.5(400)15^2 <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">:45000 J <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> b. 45000 when the KE is 0 because no energy is lost. <span style="color: #000000; font-family: arial,helvetica,sans-serif; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">c. GPE: 45000 mgh: 1/2mv^2 10(h): 1/215^2 11.48 m

9. The GPE is increasing when the ball is thrown upwards because the height increases at this time and they are directly proportional.

10. They are traveling the same height and have the same gain with GPE at the end.

11. m: .020 h:.40 v:2.7 GPE : mgh (.020)(9.8)(.40) .0784 J KE: .5(.020)(2.7^2) .0729 J a. They are very similar with .0729 J and .0784 J  b. SPE 1/2kx^2 .5: It is about .075 must be about the same epe --> gpe values should be the same if there are no losses. c. GPE: mgh: (.020 X 3)(9.8)(.40) .13m

12. a.GPE: SPE: 1/2kx^2 (300)(9.8)(18): .5k(4^2) 6600 n/m b. GPE: SPE: 1/2kx^2 (400)(9.8)(18): .5k(4^2) 4.62 m

13. KE: SPE KE: 1/2kx^2 KE: (.5)(40)(.3)^2 KE: 1.8 J

What do you think now? Roller coasters today get up to their highest point by having a track consisted of motors and gears More people = more more = more weight = more work meaning more GPE so the more people requires the more energy. The answers to these questions vary because roller coasters require electrical energy to get the car to the top of the hill. The heavier the cart the more electrical energy needed. Our experiment applied to this because when the mass of the toy was increased its height decreased.

=Section 4= What do you see? Students look very bored on a roller coaster on the moon, while students on a roller coaster on Saturn look like they are having a lot of fun. There is less gravity on the moon so the ride is not as fun. What do you think? Gravity does not have a direction which is why Australia is not actually upside down because gravity is holding it down.

Physics Talk
 * gravitational field: an influence that one object sets up in the space around it.
 * the direction of the gravitational field is the direction of the force on a mass
 * the gravitational field is stronger where the the are close together and weaker where the lines are further apart.
 * the gf field is present everywhere
 * the gf extends out to infinity.
 * inverse- square relationship: the force of gravity between two objects decreases by the sq of the distance between them.
 * newtons law of universal gravitation describes the gravitational attraction of objects for one another.
 * gravity: pulls towards the ground.
 * newtons law of universal gravitation states
 * 1) all bodies with mass attract other bodies w/ mass
 * 2) the force is proportional to the product of the two masses and gets stronger as either masses gets larger.
 * 3) the force decreases as the sq of the distance between the two bodies increases.
 * Fg: Gm1m2/r^2
 * Fg: the force between the bodies
 * f: the distance between their centers
 * m1 and m2: the masses of the bodies
 * G: universal constant equal to 6.67 X 10-^11N X m^2/kg^2

Checking Up 1. Towards the center of the room (center of the earth) 2. The gravitational field is the strongest where the lines are closets together and weaker where the lines are further. (The acceleration due to gravity is largest near Earth and gets weaker as you move further from Earth.) 3. 1/9 the original 4. gravity 5. elliptical

PTG 1.Thhe force would be 125 N when in between the two asteroids since it doubles. 1/4 of 500

2. a. 1/4 the original b. 1/9 the original c. 1/16 the original

3. We trust gravity because it has always been on earth keeping us here, we have never not had gravity which is why we trust it.

4. The difference is insignificant meaning the acceleration is the same at the bottom and top of the roller coaster.

5. a. the water on the side of the earth facing the moon. b. the water is attracted to the moon and causes a buldge...all masses are attracted to everything else. c. There is more water on the side facing the moon because there is an attraction from the moon.

6. a. With out fish would always be forced into the water and the fish would break the surface tension of the water so there would have to be something else that would act as gravity. b. Gravity holds a fish down because the mass of the fish is less than the earth.

7. a. 1/4 b. 1/9 c. 1/16 d. 4 times

8. a. Force doubles b. Force triples c. Force quadrupled d. Force halved masses are direct proportion

9.a. 4 times b. 9 times c. 16 times d. a quarter both distance are inverse proportion

10. a. The force doubles b. 9 Times c. 6 Times

Physics Plus Acceleration to the moon 1. a: v^2/r 988.5^2/3.84 X 10^8 .00254 m/s^2 2. v:d/t v: 2 X 3.14 X 3.84 X 10^8 / 2,440,800 v: 988.5 m/s v: 990 m/s 3. 990^/ 3.84 X 10^8: .0026 m/s 4. They are extremely close to each other only half a second away.

2.9 X 10^-19 s^2/m^3 : 1 A.U.

What do you think now? 1. Gravity's direction is downward. 2. People in Australia are held on Earth when they are "upside down" because they are being pushed down to the center no matter where you are on the earth you will be pulled to the center ground.

=**Section 5**= What do you see? Meat is being bought in two different scenes. On the left there is just a regular scale being pushed down while in the second picture there is math and physics and a spring scale. Mass v.s. weight with newtons Both scales are related in how they function. What do you think now? The same scale can not be used because an elephant is so large that its scale would not be fit to measure a canary because it is so small. A bathroom scale works by measuring how much force is being placed on the scale.

Physics Talk - Hooke's Law: describes the restoring force a spring exerts. the more you stretch the spring the larger the restoring force of the spring. - force exerted by the spring = -spring constant X spring stretch (or compression) Fs = -kx - Hooke's Law: Fs: -kx - F: force the spring exerts - k: spring constant - x: the stretch distance -units of force, units of spring force constant, units for stretch distance: newtons - it is negative because the force is opposite the stretch distance. - weight : mg - weight: force. interpolate: extrapolate: help predict points not measured. fs: mg only when acceleration is zero

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">Checking up <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 1. <span style="font-family: arial,helvetica,sans-serif;"> increases by 5 times. <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 2. it shows how easy or difficult it is to stretch or compress the spring. <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 3. 1-kg mass on earth = 9.8 N. <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 4. the amount of force you are putting onto the scale will determine your weight. (kg your are X 9.8)

<span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">PTG <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">1. a. w:mg <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 100 X 9.8 <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 980 N <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> b. w:mg <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 10 X 9.98 <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> =98 N <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> c. w:mg <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 60 X 9.8 <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 588 N

<span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> 2. a. .25/130 = 1/x <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> x: 520 N <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> b. .25/1000 = 1/x <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> x: 4000 N <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> c. .25/50: 1/x <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;"> x: 200 N

<span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">3. a. b. c. slope : 14.9 N/m d. slope: the spring constant e: the spring is more stretch and closer and has a less steep slope. <span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">looser spring less force required

<span style="font-family: Arial; font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">4. Fs: -kx 12: k (.03) 400 N: k

5. As the force increases the stretch will increase....linear relationship

6. The 15 the bigger the number the harder it is.

7. F:kx 3:k.02 k: 150 N/m

8. A spring scale works based upon the principles of Hookes Law. The larger the force the larger the stretch of the spring will be...they are directly proportionally with each other. If there is no acceleration the spring is going to equal the weight that is added to the spring. The equation is F: -kx

What do you think now? You cant use the same scale because their weights are so different that they would require different springs that are either much stretchier or much sterner in order to find the measurement. A bathroom scale works by measuring the force of your body on the scale.

=Section 6=

What do you see? there are two elevators that have a scale in them. One has a big man on the scale going downward and his weight is zero and one has a little boy on the scale going up and he has an actual weight.

What do you think? Your weight does not change but you feel heavier and lighter at different parts of the ride. Weight is a relative value so when there is less force on you then your weight would feel like less.

Physics Talk - an object moving downward at constant speed is identical (in terms of forces and acceleration) to the object moving up at a constant speed. - newtons law states that it is the net force acting on your that is responsible for your acceleration. - when an object accelerates there must be a net force acting upon that object. - earth pulls down on your with a force that is smaller than the force that the scale exerts on you upward. - increasing speed: velocity, and acceleration point in the same direction - decreasing speed: velocity and acceleration point in opposite directions - net force and acceleration always point in the same direction <-- says newtons second law - the bigger force is is in the same direction as net force

Checking Up 1. the sum of all the objects would be zero 2. ** the reading on the bathroom scale on the roller-coaster would be greater than the magnitude of your weight because you are accelerating up and would feel heavier. ** 3.  4. the bathroom scale would read zero, because there is no force when you are falling at the same force as the elevator. 5. air resistance

PTG

1. a. vf:vi + at (9.8)(2) 19.6 m/s b. (9,8)(5) 49 m/s c. (9.8)(10) 98 m/s

2. same equation and same given equation except the acceleration is now 1.6 <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">a. vf:vi + at <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">(1.6)(2) 3.2 m/s <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;"> b. (1.6)(5) 8m/s <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;"> c. (1.6)(10) 16 m/s

4.
 * **Motion of the Elevator** || **Acceleration (up, down, zero)** ||  || **Relative Scale Reading (greater, less or equal to weight)** ||
 * At rest, bottom floor || zero ||  || equal ||
 * Starting at Rest, Increasing Up || up ||  || greater ||
 * Continuing to move, Constant Up || zero ||  || equal ||
 * Slowing down to top floor, Decreasing Up || down ||  || less ||
 * At rest, top floor || zero ||  || equal ||
 * Starting at rest, Increasing Down || down ||  || less ||
 * Continuing to move, Constant Down || down ||  || less ||
 * Coming to a stop on the ground floor || up ||  || greater ||

<span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">5. The weight is becoming smaller from 140 to 137 pounds so it is either decreasing up or decreasing down because the direction of the acceleration is down. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">F: ma <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">Nscale - W ma <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">negative acceleration means it is pointing down. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">two arrows down which means it is increasing down <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">In opposite directions it would be decreasing.

<span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">6 Both forces are pointing up (the accel and the velocity) and this means the greater force is also pointing up just like the net force is poiting up (the normal force)

7. a. when the elevator goes down the reading will go down also n-w: ma n: ma + mg  b. 50 X -1.5 + 50 X 9.8 -75 + 490 : 415 N

8. a. At rest the elevator will read 50 kg because there will be no change since the forces are equal at this time. b. v up, a up, net force is up, up is positive N - mg: ma N : 50 X 2 + 490 N: 490 N c. At constant speed the elevator will read 50 kg because there will be no change since the forces are equal at this time when moving at a constant speed. b. v up, a up, net force is up, up is positive

9. first: there is no unbalanced force acting upon it so they must be balanced when it is at rest or at constant velocity. second: there is no normal force because everything is falling at the same rate during the free fall. The scale would read zero because zero is the only force. third: There is an unbalanced force in the direction because elevator is accelerating up for the scale reads 600 N when the force is greater at this time.

10. Our roller coaster is designed for high school teens who enjoy acceleration and would want as much acceleration as possible to make a thrilling ride. The only bad acceleration would be during turns that are not as safe.

<span style="font: normal normal normal 12px/normal Helvetica; margin: 0px; padding: 0px;">What do you think now? Your actual weight does not change, your "apparent weight" changes. Weight is a relative value so when there is less force on you then your weight would feel like less. The scale would say you are heavier at different parts of the roller coaster and light at other parts. On your way down an incline you would be lighter, while on your way up you would feel heavier.

=Section 7=

What do you see? There is a roller coaster track that has loops and twists. The carts are going around turns and the people look as if they are almost falling out.

What do you think? You do not fall out of a roller coaster when it goes up a loop because of the fast speed it is moving at.

Physics Talk
 * centripetal force: force that points to the center of the circle either normal, friction, tension, or weight
 * centripetal acceleration: if a:0, then moving in a straight line
 * tangental speed <-- constant, usually
 * F: mv^2/ R v^: accleration
 * when the radius increases the centripetal force goes down.
 * increase the mass the force increases as well, increase the velocity the force increases also.
 * acceleration, net force, bigger force: point to the center.
 * safe accelerations are less than 14
 * trained people have a safety level of 6
 * experienced more than 9 times gravity causes unconsciousness
 * Circular loops and Clothoid loops are different bc clothoid loops have two or three different radi involved while circular have a uniformed radius....you want to have to have high speeds and a small radius

Checking Up 1. Centripetal Force 2. Yes or else you wont move in a circle 3. Normal and Weight 4. Normal force 5. On the mass there is a direct relationship. On the radius there is an inverse relationship. The speed relationship is direct squared.

PTG 1. Tangent to the circle

2. a. Friction makes you move in a circular motion in a real car b. straight - tangent to the circle

6. a. No speed is only how big it is 20 m/s did not change. b. The velocity changes bc the direction did from east to north. c. change in velocity : v2 - v1 I 20 m/s N <-- 20 m/s west V20^2 + 20^2 = 28.7 m/s tan -O- == 20/20 = 45 degrees

7. v^2/r 20^2 / 200 2 m/s^2

10.

13.a. normal up weight down, a up, Fc up, : Feel heavy bc normal weight is greater than apparent weight b. normal down, weight down, a down, F down: cant tell bc normal and weight point down c. normal up weight down, a up, Fc up: Feel heavier bc normal is greater than weight d. normal up, a up, f up: Feel heavier bc normal is greater than weight. e. would have zero net force bc moving up with constant speed: You should be normal bc the net force is 0.

14. a up b up c down d. up e there is no centripetal foce bc your not moving in a circle f to the center g. to the center

Active Physics Plus 1. a. F = ma The Fnet increases if the mass increases. b. F = ma The Fnet increases also if the velocity increases.

2. a. The track must be four times stronger if the speed is doubled.

3. The Fnet gets smaller, the bigger the denominator the smaller the result.

4. - smaller - larger

5. When moving in a straight path no force is required bc it is not moving in a circle so no force is needed to keep it in the center and keep it in the circular motion just like the stopper on the string.

What do you think now? You don't fall out of a roller coaster cart because you feel pressed into your seat due to inertia. The net force points down towards the center which is why you dont fall out. Acceleration is also pointing to the center which causes you to move around the roller coaster through its loops.

=Section 8=

What do you see? A roller coaster has people pulling roller coaster carts up a steep hill and then going down the steep hill much faster. Because the roller coaster is so steep it is hard to climb up it. What do you think? It is more difficult to walk up a steep incline because the distance is not spread out and more power is needed.

Physics Talk <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">work: the product of displacement and the force in the direction of the displacement; the energy transferred to an object. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> power: work/ elapsed time - the rate of energy dissipates. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">watt: the SI unit for power; 1 W = 1 J/s <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> Work= force(parallel to the displacement) x displacement <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">Normally breaks stop the coaster cars. The breaks use friction to convert the KE of the car's motion into thermal energy. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> how to move a roller coaster? - electrical energy ( voltage, current, and time) how to stop a roller coaster? - compression of spring - make a final hill - friction (brakes system) --> makes heat - worked must be made

Check Up: 1. When a spring scale is used to do work pulling a cart to the top of an incline, where has the energy gone when the cart is at rest at the top. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;">2. KE <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> 3. The ramp makes the work gradual which makes the rate of energy being used dissipate requires less power. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> 4. acceleration goes to zero. <span style="font: normal normal normal 12px/normal Helvetica; margin: 0px;"> 5. A watt which SI unit for power; 1 W = 1 J/s

1. a. All the energy is GPE at the top at the bottom it is zero. b. GPE/ height c. all of it which is the same as the GPE = W = EPE d. 1/2kx^2 e. KE and GPE f. just when it first touches the spring.

2. a. zero b. 60/.5 = 30 N c, 75 X 40 = 3,000 N d. 500 X .7: 350 N

3. Use less of it, dont waste it. Because even if it is not in the same form it is some where.

4. There would be more mass, therefore we would need more energy and force making more work done with a higher GPE.

5. a. W: FD 10,000 X 20 = 200,000 b. 100,000/150

6. At the top of the incline work is being done then it changes to GPE then goes down the first hill and KE is being made. At the top of the vertical loop there is GPE and KE, then at the bottom just KE then KE during horizontal loop. KE is around back curve, KE going up to the second hill and GPE at the top of the second hill. During the breaking section there is work being done.

What do you think? It takes more energy to pull a roller coaster up a steep incline because more power is required. It also is more difficult to walk up a steep incline rather than a gentle incline. The steeper the incline the less time there is for the rate of energy being used to dissipate.

=Section 9=

What do you see? Too students are taking a test and thinking about when they should use force and when they should use energy. Each student is dealing with energy and force differently.

What do you think? The ride will still be fun in the loops because the rider will feel more force on them.

Physics Talk review of math is in physics plus**
 * Energy a Scalar Quantity
 * deal with energy
 * speed, distance, energy, age, time, mass
 * Force a Vector Quantity
 * includes direction, size (weight)
 * deals with force
 * Scalar Vc. Vector can i draw an arrow to represent it? displacement, acceleration, momentum : are all vectors they have a direction
 * Scalar : regular arithmetic to add
 * Vector: vector addition techniques that take into account direction.
 * same direction: add opp direction: subtract
 * rectangles: Pythagorean - trig (inverse tangent)
 * force and energy are related - change in energy requires work by force
 * Energy; scalar quantity Force: Vector quantity
 * Energy is more useful when work is involved
 * Easiest application is energy concepts is when you have heights and velocities (constantly changing systems) to one condition to another condition)
 * Work links energy and forces
 * forces cause work to be done and forces cause work to be done
 * newtons second law
 * law of conservation of energy

Checking up Questions 1. pythagorean theorem 2. Energy is scalar and force is vector 3. GPE, KE, they have the same speed at the same height, the total of GPE and KE 4. The path doesn't affect it  5. work

Physics Talk 1a b a^2+b^2=c^2 3^2+5^2= C^2 c: 6 m/s south west b. tanX : 5/5 X: 45 degrees

2.Same GPE at the top since they start from the same height. At the bottom they will have the same KE = the same velocity

3 a. distance --> scalar b. displacement --> vector c. speed --> scalar d. velocity- -->vector e. acceleration --> vector f. force --> vector g kinetic energy --> scalar h potential energy -> scalar i. work --> vector

4 a scalar b vector c scalar d vector

5. Energy : The coaster goes to the first hill and uses its ke and w to go up the hill then at the top it is converted into GPE as it goes down it is converted back to KE. Force: the longer the hill the more weight there will be that will be holding the cart down.

6 a & b  c 2 because it has a straight track. The normal force is always perpendicular to the track which makes it easier.

7a b GPE at a, b, c, and d are the same because of the same height, and the same amount of energy c KE= GPE = moving at the same speed d The other points can be ignored bc they are at the same height. GPE + KE must be equal at each point on the rollercoaster so the GPE and KE are the same. Mass and gravity are always constants here.

what do you think? When the snake is switching from left to right the ride will be the most fun because of the change in direction (which means change in velocity.) The ride would be more fun when the speed change rather than remaining constant.

= **Section 10** = what do you see? There are multiple roller coasters that have cracks in the tracks, people falling off, and people going way to fast.

what do you think Roller coasters are for thrill, amusement, and adventure. They are made to be safe, but scary. At points on the ride you feel as if you are going to fall or die but you know the ride to safe. If 1/2 of the people on roller coasters ended in death i would definitely change my mind because then the ride would be too dangerous.

Physics Talk
 * Ac: v^2/2
 * Acceleration is safe when it is below 4 gs
 * How to make acceleration safe?
 * increase radius
 * lower velocity
 * reduce height of start
 * increase height of position
 * how to fix values greater than 4 g?
 * N:mv^2/r :finding normal force

Checking Up <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">1. 4 g's or 40m/s^2 <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">2. Lower the speed or increase the radius of cirlces. <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">3. Bottom bc the KE (the velocity) is the greatest <span style="font: normal normal normal 13px/normal Arial; line-height: 19px; margin: 0px;">4. Bottom bc the passenger is pushed down into the seat.

Physics Plus 1.a. GPE: KE mgh: 1/2mv^2 9.8: 1/2 30^2 h: 4.9 m

b. v^2/R 30^2/9 100 m/s^2

c. 10 100/9.8 :10 way over 4 gs

d. 4 g: 39.2 m/s^2 a: v^2/R 39.2: v^2/9 352.8: v^2 18.8 m/s: v

e. 4 g: 39.2 m/s^2 a: v^2/R 39.2: v^2/7 247.4: v^2 16.56 m/s: v it would be smaller

f. GPE1=GPE2 +KE1 mgh1 = mgh3 + 1/2mv^2 9.8 X 45.9 = 9.8 X 18 + 1/2v3^2 449.82 = 176.4 + 1/2v9 23.4 m/s = v3

g. Ac: v^2/r 23.4^2/9 Ac3: 60.8 m/s2 6.2 gs not safe

h.You must have a minimum speed in order to make it around the loop. (look at fb and see u need normal plus weight = mass X accell...if you do not have enough speed you will fall out of your seat) if you fall normal force is 0. 9.8: Ac Ac: v^2/r 9.8:v^2/9 v: 9.4 m/s The minimum speed requirement is 9.4 m/s the max is 19.8 m/s

2. w: mg: 1000 (9.8) = 9800 N N-W=ma N: 9800 on a straight level track it is equal to your weight

3. Friction : horizontal flat track vertical : normal force loop: normal force

4. m: 1000 kg r:12m v: 15 m/s Fc: 12 X v^2/r 1000 X 15^2 /12 18750 N

5. Exactly the same 18750 N bc the same numbers as the previous question

6. a. r: 12 v: 15 m/s m: 1000 kg Fc mv^2/r 1000 X 15^2 /12 18750 N b. fb diagram into log c. w: mg: 1000(9.8) 9800 N d. n-w: mv^2/r n -9800 = 18800 N: 28,600 N

PTG 1-8 1. - Acceleration is under 4 gs - acceleration at the top of the loop has to be great than 1 g  - track has to be made up of strong enough materials to support the normal force.

2. a. mgh +1/2 mv^2 20 m

b. a: v^22/r a: 20^2/12 a: 400/12 33 m/s^2

c. no because its over 4 gs

d 4 g: 39.2 m//s 39.2: v^2/12 470.4: v^2 v: 21.69 m/s

e. 39.2 : v^2 /7 274.4: v^2 v: 16.57 m/s

3 a. 63 m/s^2 b. yes

4.a. GPE : MGH mgh: mv^2 9.8 (50) : v^2 490: v^2 v: 31 m/s

b. a: v^2/r a: 22.14 ^2/10 a: 96 m/s^2

c. v: sqr (a*r) sqr (49.02 *9.8) 22.14 m/s

d. 58 m/s

e. the acceleration is not too high

5. a. mgh: mv^2 9.8 (16) : v^2 v: 8.9 m/s

b. GPE: KE mgh: 1/2mv^2 9.8 h: 1/2 (12.52)^2 20 m

6. a. a: v^2/r 12^2/18 a: 8.0 m/s^2 b. f: mv^2/r 900 X 12^2 / 18 7200 N c. track on wheels

7. a. v^2/r 20^2/15 26.7 m/s^2 b. f: mv^2/r 900 (20)^2/15 24000 N  c. safe bc its 24,000 it can not go over 25,000

8. a.it will not change bc the mass will not affect the centripetal acceleration b. with extra passenger more strength is needed in order to go faster c. yes bc the normal force increases

What do you think now? - Knowing that people get hurt on the ride definitely enhances the thrill of the ride and makes it a more daring experience. - if i was told 1/2 of roller coaster rides ended in death i would think it still a daring experience, however, i would not ride one then. - The loops, bottom, and steep hills of an incline could be dangerous if the acceleration is above 4 gs, track is weak, and the velocity is not strong enough to make it around the circle. - I would make sure my roller coaster is safe by making the acceleration less than 4 gs, track strength, velocity has to be big enough to make it around the circle