Practice Quiz 10

Choose the best answer

  1. An object of mass 28.333 kg is located at the top
    of a 10 m tall building. Calculate the
    gravitational potential energy of the object
    with respect to a point 3 m below the top
    of the building .
    1. 1166.459 J
    2. 832.99 J
    3. 479.56 J
    4. 1259.991 J
    5. 616.244 J
    Answer: B

  2. A bullet of mass 0.0555 kg is fired from a
    15 m tall building horizontally with a speed
    of 900 m ⁄ s. Calculate its mechanical energy
    just after it is fired.
    1. 22485.659 J
    2. 42061.888 J
    3. 6988.274 J
    4. 27353.34 J
    5. 17275.824 J
    Answer: A

  3. An object of mass 9 kg is sliding down a friction less
    inclined plane of length 2 m that makes an angle
    of 70 deg with the horizontal. Calculate the
    work done by gravitational force as the object
    slides from the top of the inclined plane to the
    ground.
    1. 165.762 J
    2. 314.714 J
    3. 204.271 J
    4. 58.651 J
    5. 25.681 J
    Answer: A

  4. An object of mass 8 kg is sliding down
    a friction less inclined plane of length
    10 m that makes an angle of
    30 deg. Calculate its speed just before it hits the ground.
    1. 3.122 m ⁄ s
    2. 7.228 m ⁄ s
    3. 12.655 m ⁄ s
    4. 1.08 m ⁄ s
    5. 9.899 m ⁄ s
    Answer: E

  5. A roller coaster extends to the ground
    from a height of 31 m (point A) and then rises
    to a height of 10 m (point B). An object of mass 4 kg
    starts at point A with a speed of 5 m ⁄ s. Assuming
    the roller coaster is friction less, calculate the
    speed of the object by the time it reaches point B.
    1. 14.418 m ⁄ s
    2. 20.895 m ⁄ s
    3. 23.684 m ⁄ s
    4. 12.484 m ⁄ s
    5. 4.462 m ⁄ s
    Answer: B

  6. A certain spring extends by 0.3 m when an object
    of mass 0.4 kg hangs from it. Calculate
    the Hook's constant of the spring.
    1. 10.938 N ⁄ m
    2. 13.067 N ⁄ m
    3. 9.326 N ⁄ m
    4. 15.35 N ⁄ m
    5. 22.919 N ⁄ m
    Answer: B

  7. Calculate the elastic potential stored by a
    spring of Hook's constant 250 N ⁄ m when it is
    compressed by .1 m.
    1. 0 J
    2. 2.307 J
    3. 1.25 J
    4. 1.107 J
    5. 1.452 J
    Answer: C

  8. An object of mass 0.75 kg is brought in contact
    with a spring of Hook's constant 300 N ⁄ m that is
    compressed by 0.175 m. If the spring is let go free to expand,
    calculate the speed by which the object will
    leave the spring at its relaxed position.
    1. 2.902 m ⁄ s
    2. 2.468 m ⁄ s
    3. 6.153 m ⁄ s
    4. 1.619 m ⁄ s
    5. 3.5 m ⁄ s
    Answer: E

  9. Which of the following is not a correct statement.
    1. Work done by non-conservative forces is equal to
      the change in the mechanical energy of the object.
    2. If all the forces acting on an object are non-
      conservative, the mechanical energy is conserved
    3. Work done by conservative forces is equal to the
      the negative of the change in the potential energy of the object
    4. The force due to a spring is proportional and
      opposite to the displacement (compression or
      extension) of the spring
    5. Net work done on an object is equal to the
      change in the kinetic energy of the object.
    Answer: B

  10. Intially an object has a potential energy of 10 J
    and a kinetic energy of 170 J. Under the influence
    of conservative and non-conservative forces
    its potential energy changed to 15 J and its kinetic
    energy changed to 22 J. Calculate the work done
    by the non-conservative forces.
    1. -150 J
    2. -137 J
    3. -143 J
    4. -135 J
    5. -148 J
    Answer: C

  11. An object of mass 0.01 kg released from
    a height of 13 m has a speed of 3 m ⁄ s just before it
    hits the ground. Calculate the work done by air resistance.
    1. -1.08 J
    2. -0.728 J
    3. 0 J
    4. 0 J
    5. -1.229 J
    Answer: E