1. Work and Power

2. Work
Work is the energy necessary to move an object a distance.
Work
Not Work

3. Work(Joules) = Force (Newtons) x distance moved (meters)
Work Need to know!
Work(Joules) = Force (Newtons) x distance moved (meters)
W=Fd

4. Unit of Work Need to Know
Work is measured in newton-meters
Joule (J) = 1 Newton-meter

5. Work-Energy Theorem
If no change in energy occurs, then no work is done. Whenever work is done, energy changes.

6. “Working” out A man benches with a force of 2403 N.
The distance from his chest to the
Top of the lift is .75 m. Find the
work done :
W = F x D mg d
.5FL
.5FL

7. What is the unit of work?
Newton
Meter
Joule
Newton meter
3 and 4

8. How much work is necessary to lift a 15 kg bowling ball 5m into the air?

9. Power Need to know Power is the rate at which work is done
P = average power
P = work/time
P = W/t
Unit: Watt(w)

10. Power Example: Bench Press
If a person benches a weight of 3000 N over a distance of 0.75 m in 5 seconds, estimate the power in his chest and arms

11. How much power is required to lift 10 kg box, 5 m in the air in 10 s?

12. Power Example: Running Stairs
A 70 kg student runs up a flight of stairs in 4.0s. The height of the stairs is 4.5 m. Estimate the student’s power output in watts mg
y = 4.5