Contact & Non-Contact Forces
A force that happens when two objects touch is called what?
A contact force.
In our paper drop experiment, which fell faster: a flat sheet of paper or a crumpled paper ball?
The crumpled paper ball.
What are magnets able to do?
Push or pull certain materials.
What force caused a rubbed balloon to stick to a wall?
Static electricity.
What force pulls objects toward Earth?
Gravity.
Sort these forces into contact and non-contact:
Why did the crumpled paper ball fall faster?
It experienced less air resistance.
Will a magnet attract a wooden block? Why not?
No. The wooden block is not made of metal.
What happens when you rub a balloon on your hair?
It becomes charged.
Which experiences more air resistance: a flat sheet of paper or a crumpled paper ball?
flat sheet of paper
A charged balloon bends a stream of water without touching it. Is this a contact force or a non-contact force? How do you know?
It is a non-contact force because the balloon affects the water even though it is not touching it.
A balloon is rubbed on hair and becomes charged. What does the balloon get extra of?
Negative particles.
What happens when two north poles are pushed together?
They repel. They move away.
After rubbing on hair, a balloon gets extra:
A. Positive particles
B. Negative particles
C. Air particles
D. Heat particles
Negative particles
You drop three objects:
Put them in order from slowest to fastest.
paper airplane
flat sheet of paper
crumpled paper ball
Which force is different from the others? Explain why.
Push is different because it is a contact force. Gravity, magnetism, and static electricity are non-contact forces.
A charged balloon is brought near a stream of water. The water bends toward the balloon.
Hint 1: The balloon has extra negative particles.
Hint 2: Water has positive and negative particles.
Positive particles in the water move toward the negatively charged balloon, so the water bends.
What happens when a north pole and south pole are brought together?
They attract.
Two students rub balloons on their hair.
What is one reason Student A's balloon worked better?
Student A may have rubbed the balloon longer or created more static electricity.
A student says the paper ball falls faster because it is heavier. Another student says it falls faster because it catches less air. Who is more correct?
The second student because the paper ball experiences less air resistance.
Name TWO non-contact forces we learned.
Gravity, magnetism, static electricity.
A paper clip moves toward a magnet without being touched. What invisible thing around the magnet helps this happen?
A magnetic field.
Why is magnetism considered a non-contact force?
The force can act without the objects touching.
A student rubs a balloon on their hair and then uses it to pick up paper bits from a table.
They try again but do NOT rub the balloon this time.
What will happen the second time, and why?
The balloon will not pick up (or will pick up much less) paper because it is no longer charged without rubbing.
A student says:
"The paper helicopter falls slower because gravity pulls on it less."
Do you agree? Why or why not?
No. Gravity is still pulling on the paper helicopter. It falls slower because it experiences more air resistance.