Name: ______

Chapter 14 Study guide

  1. You calculate______by multiplying only the force acting in the direction of motion on the object by the distance the object moves.
  2. You calculate work by multiplying the ___ acting in the direction of motion by the ___ the object moves.
  3. For work to be done on the object, the object has to______
  4. The SI unit of work ______
  5. Why don’t you do work as you hold a book motionless over your head? ______
  6. Any part of a force that does not act in the direction of an object’s motion does no ______on the object.
  7. Besides a reduction in friction, the only way to increase the amount of work output of a machine is to ______
  8. A device that changes the size or direction of force used to do work is called______.
  9. The SI unit of power is ______
  10. The rate at which work is done is called ______
  11. A girl lifts a 15-N load a height of 2 m in a time of 3 s. What power does the girl produce?
  12. A worker uses a cart to move a load of bricks a distance of 5 m across a parking lot. If he pushes the cart with a constant force of 20 N, what amount of work does he do?
  13. A machine is a device that changes ______.

13. The mechanical efficiency of any machine is always ______100%.

  1. The equation for calculating a machine’s efficiency is ______
  2. Why is the work output of a machine never equal to the work input?
  3. The force that is exerted on a machine is called the ______force.
  4. Two or more simple machines working together make up a ______
  5. The actual mechanical advantage of a machine is (Less than or more than) the ideal mechanical advantage of a machine? Why?
  6. If you grease a ramp to make a box slide more easily, what happens to the ramp’s mechanical advantage?
  7. ______is used to calculate how friction affects the mechanical advantage of a simple machine?
  8. The ______of a machine is the number of times that the machine increases the input force.
  9. The distance between the fulcrum in a lever and the input force is the ______

3 Figure 14-2

24. What is the IMA of the ramp in Figure 14-2?

25. If the ramp shown in Figure 14-2 was coated with a smoother surface, how would the ramp’s efficiency change?

26. If the ramp shown in Figure 14-2 was coated with a smoother surface, how would the AMA of the ramp change?

27. A worker uses a cart to move a load of bricks a distance of 10 m across a parking lot. If he pushed the cart with a constant force of 209 N, what amount of work does he do?

28. A girl lifts a 160 N load a height of 1 m in a time of 0.5 s. What power does the girl produce?

29. A bar that is free to pivot about a fixed point is a ______.

30. Two simple machines that are part of a bicycle are a(n) ______and ______.

31. Using the figure above, if the downward force was applied by you for a distance of 2 m, how much work would you have done?

32. What is the mechanical advantage of the lever in the figure above?

33. How will a lubricant affect the efficiency of a simple machine such as a pulley?

34. An inclined plane wrapped around a cylindrical post is a ______.

35. How can a machine make work easier for you?