Grade 8 lessons 3 -4

What is Newton's Third Law of Motion?

• an object at rest stays at rest, and an object in motion will stay in motion until an outside force acts upon it

• the acceleration of an object will be equal to the net force of an object divided by its mass

• for every action, there will be an equal and opposite reaction

• an object that is not moving will stay not moving moving until an unbalanced force acts on it

If a bird hit your windshield on your car, the force of the car on the bird equals

• the force of the bird on your car.

• the force of the car on the brid

• an elastic collision on the windshield

• a noncontact force acting on the windshield

What is the net force?

• 3 N

• 3 N, right

• 17 N, right

• 3 N, left

What is the net force?

• 20 N 
• 0 N 
• 400 N 
• 40 N 

If these teams are pulling with the same amount of force what will happen?

• The boy in blue will win.
• They will not move at all.
• The boy in red will win.
• Both will fall down.

The forces in a force pair are in the _______ direction

• opposite

• same

Forces always act in equal and opposite pairs.

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction force is...

• The grip of the player's hands on the ball

• the air resistance of the ball

• the force of the ball against the bat

What is the reaction force to a foot pushing down on the floor?

• The foot going through the floor

• The floor pushing back against the foot

• The floor breaking to the foot

The amount of matter in an object.

• Weight

• Gravity

• Volume

• Mass