401 CH4 Section 1 Reading guide and Problems
  1. What is the measure of an object’s ability to do work?
  2. What is the equation for work?
  3. How do you increase the potential energy of a rubber band?
  4. Explain why sliding a block does not increase its energy?
  5. Give an example where applying force produces no work.
  6. When does a force do the most work on an object?
  7. What is the equation for work when lifting an object?
  8. Alexander has a mass of 75.6 kilograms. His apartment is on the second floor, 5.70 meters up from ground level. How much work does he do against gravity each time he climbs the stairs to his apartment?
  9. How much additional work does Alexander have to do if he is carrying 12.7 kilograms of groceries?
  10. A car engine does 62,000 J of work to accelerate at 12.2 m/sec2 for 5.00 meters. What is the mass of the car?
  11. What is Power and what are the units for power?
  12. What is one Watt equal to? What is one horsepower equal to?
  13. What is the equation for power?
  14. Explain how the weightlifters Big Mike and Little Jim do the same amount of work, but they have different amounts of power
  15. What is the maximum human power?
  16. Calculate the amount of work you do in each situation.
    a. You push a refrigerator with a force of 50 N and it moves 3 meters across the floor.
    b. You lift a box weighing 25 N to a height of 2 meters.
    c. You apply a 500 N force downward on a chair as you sit on it while eating dinner.
    d. You lift a baby with a mass of 4 kg up 1 meter out of her crib.
    e. You climb a mountain that is 1000 meters tall. Your mass is 60 kg.
  17. Sal has a weight of 500 N. How many joules of work has Sal done against gravity when he reaches 4 meters high on a rock climbing wall?
  18. You do 200 joules of work against gravity when lifting your backpack up a flight of stairs that is 4 meters tall. What is the weight of your backpack in newtons?
  19. You lift a 200 N package to a height of 2 meters in 10 seconds.
    a. How much work did you do?
    b. What was your power?
  20. One machine can perform 500 joules of work in 20 seconds. Another machine can produce 200 joules of work in 5 seconds. Which machine is more powerful?
  21. Two cranes use rope and pulley systems to lift a load from a truck to the top of a building. Crane A has twice as much power as crane B.
    a. If it takes crane A 10 seconds to lift a certain load, how much time does crane B take to lift the same load?
    b. If crane B can do 10,000 joules of work in a minute, how many joules of work can crane A do in a minute?
  22. An elevator lifts a 500 kg load up a distance of 10 meters in 8 seconds.
    a. Calculate the work done by the elevator.
    b. Calculate the elevator’s power.