Contact Forces
Noncontact Forces
Net Force
Balanced or Unbalanced
Newton's 3rd Law
100
What are the 3 types of contact forces?
Applied force
Normal force
Friction
100
What are the 2 types of noncontact force?
Gravity
Magnetism
100
What should you do with these arrows?
Add them.
100
What total net force shows that motion is balanced?
N = ZERO
N = 0
100
Every action has an ___________ and _____________ reaction.
equal
opposite
200
Explain applied force...
Applied force is a directly APPLIED push or pull.
200
Earth and the Moon attract each other through this force, even though they are not touching.
Gravity
200
A student pulls a wagon with a force of 30 N left. Friction acts with 10 N right. Calculate the net force and direction
30N-10N=20N to the left.
200
A book rests on a table. Gravity pulls downward with 5 N, and the table pushes upward with 5 N. How are the forces classified?
Balanced
200
A student presses a magnet against a refrigerator. Identify the magnetic force pair.
The magnet pulling on the refrigerator and the refrigerator pulling on the magnet.
300
A book rests on a table. Explain why the book does not move downward even though gravity pulls it toward Earth.
The upward normal force from the table balances against the gravity.
300
What noncontact force is shown here?
Magnetism
300
Calculate the net force and direction. (Pay attention to the direction of the arrows, not the side of the box they're on)
3 N Left
300
A soccer ball is kicked and begins moving from rest. What type of force caused the change in motion?
Unbalanced.
300
A student pushes a shopping cart forward. What is the reaction force to the student's push on the cart?
The shopping card pushes the students backward.
400
A student pushes a box across the floor. Identify the two contact forces acting horizontally (left and right) on the box.
Applied force and friction
400
Two magnets have their north poles facing each other. Predict what happens and explain why.
Repulsion will push like poles away from each other.
400
An object experiences 18 N right, 12 N left, and 6 N left. Determine the net force and if there is a direction.
0 N. No direction.
400
A student pushes a box with 15 N of force. Friction acts with 15 N in the opposite direction. Predict what happens to the box's motion and explain why.
The box will not move because the forces are balanced.
400
A bird pushes air downward with its wings. Identify the reaction force that helps the bird fly.
The air pushes the bird upward.
500
Two identical boxes are pushed with the same force. One moves across carpet, and the other moves across smooth tile. Predict which box will likely move easier and explain why.
The box on smooth tile, because it experiences less friction.
500
A student claims that gravity only acts on objects that are falling. Is this correct or incorrect and why?
Incorrect. Gravity is always pulling us down, and normal force is always pushing us up, even when there is no motion.
500
A box experiences 25 N to the left and 40 N to the right. How much force must be applied to the left to balance the forces?
15 N Left
500
A moving car travels at a constant speed in a straight line. What can you conclude about the forces acting on it?
The forces are balanced because no change in motion is occurring.
500
A swimmer pushes water backward. Identify the force pair and explain which force moves the swimmer forward.
The water pushes the swimmer forward.