Work Power and Energy Practice Problems
Formulas:
KE= ½ (mass x velocty²)
or
KE= (mass x velocty²) ÷ 2
PE= weight x height
or
PE= mass x acceleration due to gravity x height
Power= work ÷ time
Total Energy= KE+PE
Work= force x distance
1. Frank does 2400J of work in climbing a set of stairs. If he does the work in 6 seconds,
what is his power output?
2. How much power is required to pull a sled if you use 60J of work in 5 seconds?
3. If it takes 5 seconds for you to do 1000J of work, what is your power output?
4. A 900N mountain climber scales a 100m cliff. How much work is done by the mountain
climber?
5. A small motor does 4000J of work in 20 seconds. What is the power of the motor in
watts?
6. A woman runs a kilometer using a force of 210N and a power output of 500W. How long
in minutes does it take this woman to complete 1 kilometer?
7. A child who weighs 300N climbs a ramp to reach the top of a water slide. The top of the ramp is
20m from the ground. It takes the child 40 seconds to reach the top.
Calculate the child’s energy as they travel down the slide at 2 m/s. (Remember to get mass not weight, 300N/9.8)
Calculate the child’s energy at the top of the slide.