Newton's Law of Motion

An object moves with a constant velocity. Which of the following cannot be true for the object?

• No forces act on the object.

• A single force acts on the object.

• Two forces act on the object.

• Three forces act on the object.

An object accelerates when it experiences a non-zero net force. Which of the following statements is always true?

• The object moves in the direction of the net force.

• The object's velocity increases.

• The object's velocity is in the same direction as its acceleration.

• The object's acceleration is in the same direction as the net force that acts upon it.

A model rocket of mass m is fired upward from a launch pad with some initial speed, v. A gravitational force is exerted on the rocket

• at all points in its motion except at it highest point.

• at all points in its motion.

• at no points in its motion.

• at none of these choices.

A race car moving quickly around a track collides with a mosquito, which splatters on the car's windshield. Which object experiencesA race car moving quickly around a track collides with a mosquito, which splatters on the car's windshield. Which object experiences a greater magnitude impact force?

a greater magnitude impact force?

• Both experience the same force.

• One cannot tell; you need to know the speeds of the mosquito and the race car.

• the mosquito

• the race car

When you sit in a chair there is necessarily a reaction force to the gravitational force acting on your body. Which of the following best describes this reaction force?

• the force of gravity you exert on the Earth

• the force you exert downward on the seat of the cha

• the normal force exerted by the chair onto you

• none of these forces