Practice Quiz 8

Choose the best answer

  1. An object is being pulled on a horizontal
    surface by a horizontal force of 60 N.
    If it s moving with a uniform speed, calculate the
    force of friction exerted by the surface on the object.
    1. 60 N
    2. 588 N
    3. 646.8 N
    4. 72 N
    5. 6.122 N
    Answer: A

  2. An object of mass 100 kg is hanging from a ceiling
    by means of two strings. The first string ( T1 ) makes an
    angle of 50 degree with the horizontal-right. The second string ( T2 )
    makes an angle of 35 degree with the horizontal-left. The
    equations relating the x-components and the y-components
    of the forces acting on the object respectively are
    1. -0.643 * T1 + 0.819 * T2 = 0
      0.766 * T1 + 0.574 * T2 - 980       N = 0
    2. 0.766 * T1 + 0.574 * T2 = 0
      -0.643 * T1 + 0.819 * T2 - 980       N = 0
    3. -0.643 * T1 + 0.574 * T2 = 0
      -0.643 * T1 + 0.574 * T2 - 980       N = 0
    4. -0.643 * T1 + 0.819 * T2 - 980 N = 0
      0.766 * T1 + 0.574 * T2 = 0
    5. 0.766 * T1 + 0.574 * T2 - 980 N = 0
      -0.643 * T1 + 0.819 * T2 = 0
    Answer: A

  3. An object of mass 400 kg is hanging from a ceiling
    by means of two strings. The first string ( T1 ) makes an
    angle of 20 degree with the horizontal-right. The second string
    ( T2 ) makes an angle of 55 degree with the horizontal-left.
    Calculate the tension in the first string ( T1 )
    1. 3343.04 N
    2. 1391.735 N
    3. 2327.735 N
    4. 4235.522 N
    5. 3660.916 N
    Answer: C

  4. An object of mass 60 kg is being pulled on
    a friction less horizontal surface by means of
    a string that makes an angle of 60 degree with the
    horizontal. If the tension in the string is 60 N
    calculate the acceleration of the object.
    1. 1.732 m ⁄ s 2
    2. 9.8 m ⁄ s 2
    3. 0.866 m ⁄ s 2
    4. 1 m ⁄ s 2
    5. 0.5 m ⁄ s 2
    Answer: E

  5. An object of mass 28 kg is being pulled on a
    friction less horizontal surface by means of two
    strings. One of the strings has a tension of 30 N and makes
    an angle of 80 degree with the horizontal. The other string is
    pulling horizontally and has a tension of 14 N.
    Calculate the acceleration of the object.
    1. 1.024 m ⁄ s 2
    2. 0.686 m ⁄ s 2
    3. 0.11 m ⁄ s 2
    4. 0.41 m ⁄ s 2
    5. 0.2 m ⁄ s 2
    Answer: B

  6. An object of mass 280 kg is being pulled on a friction less
    horizontal surface by means of two strings. One of the strings
    is pulling forward, has a tension of 600 N and makes
    an angle of 30 degree with the horizontal-right. The other string is
    pulling backwards horizontally and has a tension of 18 N.
    Calculate the acceleration of the object.
    1. 1.791 m ⁄ s 2
    2. 0.946 m ⁄ s 2
    3. 0.306 m ⁄ s 2
    4. 2.104 m ⁄ s 2
    5. 2.408 m ⁄ s 2
    Answer: A

  7. An object of mass 6 kg is being pulled on a horizontal
    surface by a string that makes an angle of
    50 degree with the horizontal. The tension in the string is 13 N.
    Calculate the normal force exerted by the ground on the object.
    1. 48.841 N
    2. 82.081 N
    3. 59.52 N
    4. 5.726 N
    5. 68.383 N
    Answer: A

  8. An object is of mass 42 kg is beng pulled on a horizontal
    surface by a string that makes an angle of 15 deg
    with the horizontal. The tension in the string is 340 N.
    The coefficient of kinetic friction of the surfaces is 0.45.
    Calculate the acceleration of the object.
    1. 4.862 m ⁄ s 2
    2. 7.471 m ⁄ s 2
    3. 5.465 m ⁄ s 2
    4. 4.352 m ⁄ s 2
    5. 2.506 m ⁄ s 2
    Answer: D

  9. An object of mass 28 kg is sliding down a friction less
    inclined plane that makes an angle of 20 deg with the horizontal.
    Calculate the component of gravitational force that is
    pulling the object along the inclined plane.
    1. 3.352 N
    2. 274.4 N
    3. 257.852 N
    4. 93.85 N
    5. 9.209 N
    Answer: D

  10. A 20 kg object and a 7 kg object are
    attached by a string. If the 7 kg object is being pulled
    by a force of 180 N. Calculate their acceleration.
    1. 9 m ⁄ s 2
    2. 0.68 m ⁄ s 2
    3. 6.667 m ⁄ s 2
    4. 5.333 m ⁄ s 2
    5. 25.714 m ⁄ s 2
    Answer: C