Quiz 7:

1. Newton's first law states that...

• A. An object will remain at rest or move with a constant speed unless acted upon by a net force.
• B. The force acting on an object is directly proportional to the acceleration produced by the force.
• C. An object will remain at rest unless acted upon by a net force.
• D. For every action there is an equal but opposite reaction.
• E. An object will remain at rest or move in a straight line with a constant speed unless acted upon by a net force.

2. Which of the following situations can be explained by Newton's first law?

• A. When the brakes of a car are applied suddenly, the body of the driver jerks forward.
• B. When the force acting on an object is doubled, its acceleration is doubled.
• C. When the force acting on an object is doubled, its acceleration is halved.
• D. When a man fires a gun, his body jerks backward.
• E. A swimmer pushing the water backward to move forward.

3. Mass of an object is...

• A. the same as the weight of the object.
• B. different on different planets.
• C. a measure of the gravitational force exerted on the object by the massive object in the vicinity of the object.
• D. measured in terms of Newtons.
• E. a measure of the amount of matter the object has.

4. Calculate the force acting on a 5.876 kg object moving with an acceleration of 24 m ⁄ s ².

• A. 141.024 N
• B. 244.43 N
• C. 81.34 N
• D. 104.483 N
• E. 16.356 N

5. Calculate the mass of an object whose weight is 1133 N.

• A. 115.612 kg
• B. 64.004 kg
• C. 81.713 kg
• D. 175.671 kg
• E. 134.24 kg

6. Under the influence of a certain force the velocity of a 5 kg object increased from 28.445 m ⁄ s to 48 m ⁄ s in 90 seconds. Calculate the force exerted on the object.

• A. 1.79 N
• B. 1.086 N
• C. 1.346 N
• D. 1.925 N
• E. 0.896 N

7. The component of the surface force between two surfaces sliding on each other parallel to the surface is called

• A. friction
• B. sliding force
• C. normal force
• D. contact force
• E. gravitational force

8. Which of the following statements is not correct?

• A. The force required to just get an object sliding is bigger than the force required to get it sliding once it has started sliding.
• B. Force of friction does not depend on the relative speed between the sliding surfaces.
• C. Coefficient of friction is unit less.
• D. Coefficient of friction is equal to the ratio of force of friction to normal force.
• E. Force of friction depends on the area of the surfaces in contact.

9. An object of mass 48.555 kg is sliding on a horizontal surface. Calculate the normal force exerted by the surface on the object.

• A. 392.21 N
• B. 256.694 N
• C. 475.839 N
• D. 566.696 N
• E. 308.748 N

10. An object of mass 54.221 kg is sliding on a horizontal surface with a uniform speed. The coefficient of kinetic fiction of the surfaces is 0.35. Calculate the force of friction exerted by the surface on the object.

• A. 185.978 N
• B. 236.564 N
• C. 121.49 N
• D. 294.325 N
• E. 32.235 N

11. An object of mass 9.665 kg is being pulled by a horizontal force of 270 N on a horizontal force. The coefficient of kinetic friction between the object and the surface is 0.15. Calculate the acceleration of the object.

• A. 26.466 m ⁄ s ²
• B. 30.994 m ⁄ s ²
• C. 18.149 m ⁄ s ²
• D. 38.921 m ⁄ s ²
• E. 21.384 m ⁄ s ²