Quiz 8:

1. An object is being pulled on a horizontal surface with a horizontal force of 105 N. If it is moving with a uniform speed and the coefficient of friction between the sliding surfaces is 0.5 , calculate the normal force exerted by the surface on the object.

• A. 105 N
• B. 210 N
• C. 252 N
• D. 0.007 N
• E. 52.5 N

2. An object of mass 400 kg is hanging from a ceiling by means of two strings. The first string ( T₁ ) makes an angle of 25 degree with the horizontal-right. The second string ( T₂ ) makes an angle of 20 degree with the horizontal-left. The equations relating the x-components and the y-components of the forces acting on the object respectively are

• A. 0.423 * T₂ + 0.342 * T₂ = 0
  -0.906 * T₁ + 0.94 * T₂ - 3920 N = 0
• B. -0.906 * T₁ + 0.94 * T₂ - 3920 N = 0
  0.423 * T₁ + 0.342 * T₂ = 0
• C. -0.906 * T₁ + 0.94 * T₂ = 0
  0.423 * T₁ + 0.342 * T₂ - 3920 N = 0
• D. -0.906 * T₁ + 0.342 * T₂ = 0
  -0.906 * T₁ + 0.342 * T₂ - 3920 N = 0
• E. 0.423 * T₁ + 0.342 * T₂ - 3920 N = 0
  -0.906 * T₁ + 0.94 * T₂ = 0

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 25 degree with the horizontal-right. The second string ( T₂ ) makes an angle of 25 degree with the horizontal-left. Calculate the tension in the first string ( T₁ )

• A. 8330.21 N
• B. 7639.846 N
• C. 4637.755 N
• D. 5930.302 N
• E. 3598.951 N

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 20 degree with the horizontal. If the tension in the string is 60 N calculate the acceleration of the object.

• A. 0.94 m ⁄ s ²
• B. 0.364 m ⁄ s ²
• C. 9.8 m ⁄ s ²
• D. 1 m ⁄ s ²
• E. 0.342 m ⁄ s ²

5. An object of mass 36 kg is being pulled on a friction less horizontal surface by means of two strings. One of the strings has a tension of 60 N and makes an angle of 40 degree with the horizontal. The other string is pulling horizontally and has a tension of 8 N. Calculate the acceleration of the object.

• A. 0.733 m ⁄ s ²
• B. 1.499 m ⁄ s ²
• C. 0.908 m ⁄ s ²
• D. 2.536 m ⁄ s ²
• E. 2.226 m ⁄ s ²

6. An object of mass 40 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 120 N and makes an angle of 20 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.

• A. 2.369 m ⁄ s ²
• B. 2.985 m ⁄ s ²
• C. 2.719 m ⁄ s ²
• D. 4.15 m ⁄ s ²
• E. 1.309 m ⁄ s ²

7. An object of mass 2 kg is being pulled on a horizontal surface by a string that makes an angle of 20 degree with the horizontal. The tension in the string is 13 N. Calculate the normal force exerted by the ground on the object.

• A. 8.889 N
• B. 19.346 N
• C. 15.154 N
• D. 4.982 N
• E. 13.438 N

8. An object is of mass 50 kg is beng pulled on a horizontal surface by a string that makes an angle of 10 deg with the horizontal. The tension in the string is 260 N. The coefficient of kinetic friction of the surfaces is 0.45. Calculate the acceleration of the object.

• A. 1.688 m ⁄ s ²
• B. 0.498 m ⁄ s ²
• C. 1.832 m ⁄ s ²
• D. 1.519 m ⁄ s ²
• E. 1.117 m ⁄ s ²

9. An object of mass 28 kg is sliding down a friction less inclined plane that makes an angle of 80 deg with the horizontal. Calculate the component of gravitational force that pushes the object against the plane in a direction perpendicular to the inclined plane.

• A. 274.4 N
• B. 9.651 N
• C. 270.231 N
• D. 47.649 N
• E. 1.702 N

10. A 10 kg object and a 15 kg object are attached by a string. If the 15 kg object is being pulled by a force of 220 N. Calculate their acceleration.

• A. 7.04 m ⁄ s ²
• B. 8.8 m ⁄ s ²
• C. 14.667 m ⁄ s ²
• D. 0.898 m ⁄ s ²
• E. 22 m ⁄ s ²