Force & Motion
What is a force?
Answer: A push or pull on an object.
Two people push a box with equal force in opposite directions. Are the forces balanced or unbalanced?
Answer: Balanced.
What is mass?
Answer: The amount of matter in an object.
Newton’s Third Law says every action force has what?
Answer: An equal and opposite reaction force.
What does direction tell us?
Answer: The path or way an object is moving.
What is motion?
Answer: A change in an object’s position over time.
What is the net force when 5 N pushes right and 5 N pushes left?
Answer: 0 N.
What is acceleration?
Answer: A change in an object’s speed or direction.
You push against a wall. What does the wall do?
Answer: The wall pushes back on you with an equal force in the opposite direction.
What is a frame of reference?
Answer: Something used to compare or describe an object's position or motion.
What unit is used to measure force?
Answer: Newtons (N).
A box has 10 N pushing right and 4 N pushing left. What is the net force?
Answer: 6 N to the right.
Which is easier to accelerate with the same force: an empty shopping cart or a full shopping cart?
Answer: The empty shopping cart.
A swimmer pushes water backward. What happens to the swimmer?
Answer: The water pushes the swimmer forward.
You are sitting inside a moving car. Relative to your seat, are you moving?
Answer: No. Relative to the seat, you are not moving.
Name three ways a force can change an object’s motion.
Answer: Speed it up, slow it down, or change its direction.
If an object's motion is changing, are the forces balanced or unbalanced?
Answer: Unbalanced.
If you apply more force to the same object, what happens to its acceleration?
Answer: Its acceleration increases.
A basketball pushes down on the floor when it bounces. What is the reaction force?
Answer: The floor pushes upward on the basketball.
Car A travels east at 30 mph. Car B travels east at 20 mph. How fast is Car A moving relative to Car B?
Answer: 10 mph east.
A soccer ball is sitting still. A player kicks it and the ball begins moving. Explain what caused the change in motion.
Answer: The kick applied a force to the ball, causing it to accelerate and move.
A cart has 15 N pushing left and 9 N pushing right. Find the net force and predict the direction of acceleration.
Answer: 6 N to the left. The cart accelerates left.
Two carts are pushed with the same force. Cart A has more mass than Cart B. Which cart will accelerate more? Explain.
Answer: Cart B because it has less mass.
If action-reaction forces are equal and opposite, why don't they cancel each other out?
Answer: Because they act on two different objects.
A bowling ball hits a bowling pin. The ball pushes the pin with 20 N. How much force does the pin exert on the ball, and in what direction?
Answer: 20 N in the opposite direction.