Chapter 12 review


    Standardized test practice
    1. Scott has a machine with a mechanical advantage of five. How much force does he need to apply to create an output force of 120 N?

      1. 5 N
      2. 24 N
      3. 125 N
      4. 6,000 N
    2. A lever with an output arm of length 40 cm has an object on the end of it. Larisa pushes on the 80 cm input arm with 100 N of force to balance the lever. What is the mass of the object?

      1. 2.0 kg
      2. 10.2 kg
      3. 20.4 kg
      4. 204 kg
    3. Rafi uses a pulley system to lift a 15 N weight by 6 m. If he pulls his end of the rope a distance of 3 m, which of the following would be the force he uses? (Assume the pulley is 100% efficient.)

      1. 5 N
      2. 15 N
      3. 25 N
      4. 30 N
    4. Katarina pushes a 41 kg crate up a ramp 7.5 m long. In going from the bottom of the ramp to the top, she raises the crate 1.5 m while doing 1,000 J of work. Which of the following is most nearly the efficiency of the ramp?

      1. 0.20
      2. 0.30
      3. 0.40
      4. 0.60
    5. Which of the following simple machines provides the least mechanical advantage?

      1. A lever 1 m long whose fulcrum is 80 cm from the input force and 20 cm from the load.
      2. A block-and-tackle assembly that lifts a 1,000 N load when you provide a 200 N input force.
      3. A wedge with 80-mm-long sides and a base 10 mm wide.
      4. All three machines are equally efficient.
    6. Which of the following pieces of equipment is the best choice for measuring force?

      1. spring scale
      2. triple beam balance
      3. meter stick
      4. friction block
    1. Which of the following is the best choice to provide the widest variety of different values of mass?

      1. a set of seven hooked lab masses, each having a different mass
      2. a set of five slotted masses, each with a different mass
      3. a hanging plastic bottle with water
      4. a set of 25 identical marbles
    2. Cristin and Adele built a block-and-tackle assembly to lift a 20 kg motor. They had to pull their end of the rope with an input force of 100 N. Furthermore, they had to move their end a distance of 2.5 m to lift the motor just 50 cm. What was the ideal mechanical advantage of the block-and-tackle assembly?

      1. 0.05
      2. 0.5
      3. 2.5
      4. 5
    3. How many turns will the 52-tooth gear make?
    4. A 15-tooth gear makes 20 turns. How many turns will the 52-tooth gear make?

      1. 2.60
      2. 3.67
      3. 5.77
      4. 10.00
    5. Suppose that a compound machine is made by connecting a wheel-and-axle assembly with a mechanical advantage of 4.0 to a block-and-tackle assembly with a mechanical advantage of 5.0. What will be the mechanical advantage of the machine as a whole?

      1. 0.8
      2. 1.25
      3. 9.0
      4. 20
    6. Suppose that a compound machine is made by connecting a wheel-and-axle assembly with an efficiency of 0.80 to a block-and-tackle assembly with an efficiency of 0.50. What will be the efficiency of the machine as a whole?

      1. 0.3
      2. 0.4
      3. 1.3
      4. 1.6

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