Force and Motion

The rate an object accelerates depends on __________.

• whether it is already moving

• its mass and the strength of the force

• how long the force acts on it

• the direction of the force

If two opposite forces act on a stationary object at the same time, and one pushes north at 16 newtons and the other pushes south at 12 newtons, which way will the object move?

• It will not move.

• east or west

• north

• south

What does Newton's third law of motion state?

• If you push something hard enough, it will fall over.

• For every action there is an equal and opposite reaction.

• Force equals mass times acceleration

• An object in motion will remain in motion unless acted upon by another object.

The force that one surface exerts on another when the two rub against each other is called ___________.

• gravity

• friction

• energy

• electricity

A ball rolling along a smooth sidewalk suddenly rolls onto a grassy area. What will happen to the ball’s motion?

• It will roll faster because friction increases.

• It will roll faster because friction decreases.

• It will roll slower because friction increases.

• It will roll slower because friction decreases.

What effect does friction have on a moving object?

• It causes the moving object to slow and eventually stop.

• It causes the moving object to speed up.

• It keeps the moving object moving in the same direction forever.

• It causes the moving object to turn around and move in the opposite direction.

The speed and direction of an object's motion is its ___________.

• momentum

• inertia

• velocity

• mass

A force acting on an object will cause it to __________.

• increase its mass

• move at a constant speed

• decrease its mass

• accelerate

If two opposite forces act on a stationary object at the same time, and one is stronger than the other, which way will the object move?

• It will move toward the stronger force.

• It will move toward the weaker force.

• It will move at right angles to the two forces.

• It will not move.

What does Newton's Cradle demonstrate?

• that every action has an equal and opposite reaction

• conservation of speed

• the effect of friction

• the acceleration of objects