1. WARM UP
1)How much potential energy does a 20 kg child have when she is 4 m up in a tree?
2) When would you observe elastic potential energy?
3) A spring with a spring constant of k = 2 kg/s2 is compressed 4 m. how much energy is stored in the spring?

2. LEARNING GOALS Define work
Calculate the amount of work done by a constant force
Define and calculate Power

3. Work Work is a process which changes the amount of energy in a system
There are two ways to find the amount of work done
1) Work = change in energy
W = ΔE
2) Work = force x distance
W = Fd

4. Examples REMEMBER: work is measured in Joules Change in energy
The amount of energy in a system increases by 12 J, how much work was done on the system?
Work done by a constant force
A 15 N force pushes a stubborn pony 4 m. How much work did the force do?

5. Together Change in energy
How much work must be done on a system to increase its energy by 4000 J?
Work done by a constant force
A 30 N force pushes an armadillo 2 m. How much work did the force do?

6. Practice Change in energy
The amount of energy in a system increases by J, how much work was done on the system?
Work done by a constant force
A 3 N force pushes Mr. Baden 12 m. How much work did the force do?

7. WORKSHEET

8. Roller Coaster Cutting

9. Power Power = work divided by time P = W / t
The unit for power is the Watt (W)

10. Practice
40 J of work are done on a box of chocolates in 10 s. How much power was used to do this?

11. COOL DOWN
1) How much work does it take to increase the amount of energy in a car by J?
2) 10 N of force are applied over a distance of 9 m. How much work was done by the force?