Unit 5 Physics

An object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity unless acted upon by a net external force. Which of Newton's Laws of Motion does this statement describe?

• Newton's First Law

• Newton's Second Law

• Newton's Third Law

• None of the above

What does it mean for an object to be in a state of equilibrium?

• The object has a net force acting on it, causing it to accelerate.

• The object is at rest, and no forces are acting on it.

• The object has a net force of zero, so its motion is constant (either at rest or moving at a constant velocity).

• The object is only at rest, not moving at all.

Which of the following is a real-world example of Newton's First Law (inertia)?

• A car accelerating as the driver presses the gas pedal.

• The recoil of a gun after it is fired.

• A person lurching forward when a car stops suddenly.

• A rocket launching into space.

If you apply a constant force to an object, but you double the object's mass, how will its acceleration change?

• The acceleration will double.

• The acceleration will be cut in half.

• The acceleration will stay the same.

• The acceleration will be four times greater.

If you push a cart with a larger force, what will happen to its acceleration (assuming its mass stays the same)?

• The acceleration will decrease.

• The acceleration will increase.

• The acceleration will stay the same.

• The acceleration will be zero.

The relationship between force, mass, and acceleration is best described by which of Newton's laws?

• Newton's First Law

• Newton's Third Law

• Newton's Second Law

• All of the above

When a rocket expels gases downward, the gases exert an equal and opposite force on the rocket, pushing it upward. This is an example of:

• Newton's Third Law

• Newton's First Law

• Newton's Second Law

• The Law of Universal Gravitation

Which of the following is an example of an action-reaction force pair?

• A person pushing a door and the door swinging open.

• The force of a bat on a ball and the force of the bat on the air.

• The force of a foot on a soccer ball and the force of the ball on the foot.

• The force of gravity on a ball and the ball's motion toward the ground.

A seatbelt is an essential safety device because it helps to reduce the force on a passenger during a collision. Which of Newton's laws best explains the function of a seatbelt?

• Newton's First Law, because the seatbelt keeps the person from moving.

• Newton's Second Law, because it increases the time it takes for the person to stop, reducing the force on them.

• Newton's Third Law, because the seatbelt and the person exert equal and opposite forces on each other.

• All of the above, because they all contribute to the final outcome.

A student pushes a tennis ball and a bowling ball with the same force. The tennis ball moves away with a much greater acceleration. This is because:

• The student applied a greater force to the tennis ball.

• The tennis ball has less mass, so it has less inertia.

• The bowling ball has a greater mass and therefore a greater acceleration.

• The forces are equal and opposite, and therefore the accelerations must also be equal.