Question

Work and Power Practice Calculations

W = Fd P = W/t
1. A force of 20 N was used to push a box along the floor a distance of 6 m. How much work was done?
2. It took 60 J to push a table 2 m across the floor. With what force was the table pushed?
3. If 350 J of work are used to lift a 85 N box, how high is the box lifted?
4. How much power is used if a force of 45 N is used to push a box of books a distance of 9 m in 10 s?
5. How much work is done using a 500 watt microwave for 2 minutes (120 seconds)?
6. How long would it take a crane to do 550 J of work while using a power of 310 watts?

Answer 1

1. W = F d = 20 N * 6 m = 120 J

2. F = W / d = 60 J / 2 m = 30 N

3. d = W / F = 350 J / 85 N = 4.12 m

4. P = W / t = F d / t = 45 N * 9 m / 10 s = 40.5 Watts

5. W = P t = 500 W * 120 sec = 60,000 J

6. t = W / P = 550 J / 310 W = 1.77 sec