Chapter 13 review

    Standardized test practice
    1. Which pair of mass and length gives the lowest moment of inertia for a uniform metal bar spun around its end?
      1. 5 kg, 5 cm
      2. 10 kg, 5 cm
      3. 5 kg, 10 cm
      4. 10 kg, 10 cm

    2. Which statement best describes the Earth’s motions?
      1. The Earth rotates about its axis and the Sun.
      2. The Earth revolves about its axis and the Sun.
      3. The Earth revolves about its axis while rotating around the Sun.
      4. The Earth rotates about its axis while revolving around the Sun.

    3. The formula for the angular momentum of a point mass is L = mvr. Which of the following quantities can be the SI unit for angular momentum?
      1. kg m/s
      2. kg m2/s
      3. kg m/s2
      4. kg m2/s2

    4. A quarter-kilogram (0.25 kg) tetherball is attached to a pole by a 2 m length of rope. If the tetherball circles the pole once in 0.2 s (and the rope is horizontal), how fast does it travel?
      1. 10 m/s
      2. 20 m/s
      3. 31 m/s
      4. 63 m/s

    5. A quarter-kilogram (0.25 kg) tetherball is attached to a pole by a 2 m length of rope. If the tetherball circles the pole once in 0.2 s (and the rope is horizontal), what is its angular momentum?
      1. 25 kg m2/s
      2. 31 kg m2/s
      3. 63 kg m2/s
      4. 78 kg m2/s

    6. An ice skater sets herself spinning in place with her arms outstretched. She then pulls her arms in close to her body. Which of the following can be explained by the law of conservation of angular momentum?
      1. She appears smaller.
      2. She spins faster.
      3. She eventually stops spinning.
      4. None of the above.

    1. An object’s center of mass can be outside of the object itself. Which of the following objects does not contain its own center of mass?
      1. calculator
      2. eraser
      3. pencil
      4. paper clip

    2. Wheel 1 has a larger moment of inertia than Wheel 2. Which statement best explains this fact?
      1. Wheel 1 is harder to start spinning.
      2. Wheel 1 is harder to stop spinning.
      3. Both a and b are correct.
      4. Neither a nor b is correct.

    3. Two identical metal spheres are placed at the top of a wooden ramp and then released. Sphere 1 has been oiled, and it slides down without rolling. Sphere 2 has not been oiled, and it rolls down, since friction prevents it from sliding. Which sphere will reach the bottom of the ramp first? (Assume that there is no air resistance.)
      1. Sphere 1 will reach the bottom of the ramp first.
      2. Sphere 2 will reach the bottom of the ramp first.
      3. The two reach the bottom at the same time.
      4. You cannot tell without more information.

    4. Two metal spheres are placed at the top of a wooden ramp. The spheres have identical masses and radii. Sphere 1 is hollow, with its mass all contained in a thin outer shell. Sphere 2, by contrast, is solid with its mass uniformly distributed throughout its volume. The two spheres are released at the same time and roll toward the bottom of the ramp. Which reaches the bottom first?
      1. Sphere 1 will reach the bottom of the ramp first.
      2. Sphere 2 will reach the bottom of the ramp first.
      3. The two will reach the bottom at the same time.
      4. You cannot tell without more information.

    5. Which of the following is a reason for a student to use a computer instead of pen and paper to write her investigation report?
      1. It is easy to make changes on the computer version of her report and print out a new copy, but it takes much longer to recopy the pen and paper version.
      2. The computer copy is easier to read than most people’s handwriting.
      3. With the computer, it is easier to share drafts with other members of her group when submitting a joint report.
      4. All of the above.

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