(Multiple Choice)

(1)

An object is observed to be moving at constant velocity in an inertial reference frame. It follows that 

(a) No forces act on the object. 

(b) A constant force acts on the object in the direction of motion. 

(c) The net force acting on the object is zero. 

(d) The net force acting on the object is equal and opposite to its weight.

(2)

A body moves with constant speed in a straight line in an inertial reference frame. Which of the following statements must be true? 

(a) No force acts on the body. 

(b) A single constant force acts on the body in the direction of motion. 

(c) A single constant force acts on the body in the direction opposite to the motion. 

(d) A net force of zero acts on the body. 

(e) A constant net force acts on the body in the direction of motion.

(3)

A particle of mass m is traveling at an initial speed v₀ = 25.0 m/s. It is brought to rest in a distance of 62.5 m when a net force of 15.0 N acts on it. What is m? 

(a) 37.5 kg 

(b) 3.00 kg 

(c) 1.50 kg

(d) 6.00 kg

(e) 3.75 kg

(4)

On the moon, the acceleration due to gravity is only about 1/6 of that on earth. An astronaut whose weight on earth is 600 N travels to the lunar surface. His mass as measured on the moon will be 

(a) 600 kg. 

(b) 100 kg. 

(c) 61.2 kg. 

(d) 9.81 kg. 

(e) 360 kg.

(5)

Find the weight of a 54-kg girl in 

(a) Newton’s and 

(b) Pounds.

(6) 

True or false: 

(a) Action-reaction forces never act on the same object. 

(b) Action equals reaction only if the objects are not accelerating.

(7)

An 80-kg man on ice skates pushes a 40-kg boy also on skates with a force of 100 N. The force exerted by the boy on the man is 

(a) 200 N. 

(b) 100 N. 

(c) 50 N. 

(d) 40 N.

(8)

A boy holds a bird in his hand. The reaction 35 force to the force exerted on the bird by the boy's hand is 

(a) The force of the earth on the bird. 

(b) The force of the bird on the earth. 

(c) The force of the hand on the bird. 

(d) The force of the bird on the hand. 

(e) The force of the earth on the hand. 

The reaction force to the weight of the bird is 

(a) The force of the earth on the bird. 

(b) The force of the bird on the earth. 

(c) The force of the hand on the bird. 

(d) The force of the bird on the hand. 

(e) The force of the earth on the hand.