1. Roller coasters! LO: To describe the transfer between potential and kinetic energy True or false: 1)The equation to calculate Power is Power = Work ÷Time. 2)It requires more Power to run up the stairs than walk up the stairs. 3)If I do 100J of work in 20 seconds then the Power I use is 10W 4)If I do 50J of work in 10 seconds then the Power I use is 5W. 5)If I rearrange the Power equation, then Work = Power ÷ Time

2. Roller coaster ride: http://www.youtube.com/watch?v=XIOK73JN V3A http://www.youtube.com/watch?v=XIOK73JN V3A

3. Potential Energy When does the roller coaster have the biggest ‘potential’ to release energy? A) at the bottom of the hill (before going up) B) at the top of the hill C) at the bottom of the hill (after coming down) Answer: B - at it’s highest point it has the most ‘potential’ to release energy

4. Kinetic Energy When does the roller coaster have the biggest movement energy? A) at the bottom of the hill (before going up) B) at the top of the hill C) at the bottom of the hill (after coming down) Answer: C - it is at it’s fastest point – when it has no potential energy left and it has all been turned into kinetic energy.

5. Watch this! http://www.youtube.com/watch?v=tlHDDzfP4_4 What can you say about the amount of kinetic energy given to it as it accelerates?

6. The science of roller coasters The roller coaster is given ‘ movement energy ’ by electromagnets at the start This ‘ movement energy ’ needs to be enough to get the roller coaster over the high point of the ride. As the ride slows, and it gets higher, more and more of the kinetic energy is transferred into potential energy. When it is stopped at the top, the ride only has ‘ potential energy ’. As the ride begins to fall backwards the ‘ potential energy ’ is transferred back into kinetic or movement energy.

7. What about this roller coaster? 1 2 3 4 Question: Order these positions from high to low for: 1) Potential Energy 2) Kinetic Energy

8. What about this roller coaster? 1 2 3 4 Answer: Order these positions from highest to lowest points for: 1) Potential Energy 1, 3, 2, 4 2) Kinetic Energy4, 2, 3, 1

9. Good! If you have worked out the correct answers, or know why you got them wrong…. You can now work out how we CALCULATE potential energy or kinetic energy.

10. What factors affect the ‘potential to release energy’? Consider if in each situation the underlined word affects the ‘potential energy’ A 1kg mass hanging at a height of 1 m or 2 m? A blue coloured 1kg mass or a red 1kg mass hanging at 1m? A 1 or 2 kg mass hanging at 1m? A hot or a cold 1 kg mass hanging at 1m? A 1 kg mass hanging at 1m in Earth’s gravity or the moons gravity?

11. What factors affect the ‘potential to release energy’? Does the underlined word affect the potential energy? A 1kg mass hanging at a height of 1 m or 2m? YES A blue coloured 1kg mass or a red 1kg mass hanging at 1m? NO A 1 or 2 kg mass hanging at 1m? YES A hot or a cold 1 kg mass hanging at 1m? NO A 1 kg mass hanging at 1m in Earth’s gravity or the moons gravity? YES

12. Easy: So, you correctly identified that Potential energy relies on mass, height and the strength of gravity: Copy this: E p = m g h m = mass (kg) g = gravity strength h = height (m)

13. What factors affect the ‘kinetic energy’? Consider if in each situation the underlined word affects the ‘kinetic energy’ A 1kg mass at a speed of 10m/s or 20m/s? A blue coloured 1kg mass or a red 1kg mass moving at 10m/s? A 1 or 2 kg mass moving at 10m/s? A hot or a cold 1 kg mass moving at 10m/s? A 1 kg mass moving at 10m/s in Earth’s gravity or the moons gravity?

14. What factors affect the ‘kinetic energy’? Consider if in each situation the underlined word affects the ‘kinetic energy’ A 1kg mass at a speed of 10m/s or 20m/s? YES A blue coloured 1kg mass or a red 1kg mass moving at 10m/s? NO A 1 or 2 kg mass moving at 10m/s? YES A hot or a cold 1 kg mass moving at 10m/s? NO A 1 kg mass moving at 10m/s in Earth’s gravity or the moons gravity? NO

15. Easy: So, you correctly identified that Kinetic energy relies on mass, and the speed: Copy this: E k = ½ m v 2 m = mass (kg) v = velocity h = height (m)

16. How to use this equation: E k = ½ x m x v 2 m = mass (kg) v = velocity h = height (m) e.g. 1kg moving at a speed of 10m/s E k = ½ x m x v 2 = 0.5 x 1 x (10 x 10) = 50 J