Gravity
This force pulls objects toward the Earth.
What is Gravity?
These are the two poles of a magnet
What is North and South?
There are the two types of electric charges.
A student pushes a desk
What is contact?
Does gravity require objects to touch?
No
This happens when two north poles are brought together
What is repel?
What is attract?
A magnet pulls a paper clip without touching it.
What is non-contact?
A balloon rubbed on hair attracts small pieces of paper. What type of force is responsible?
Electric force
Why does a basketball return toward the ground after being thrown upward?
Earth's gravity pulls it toward Earth.
A magnet moves a paper clip before touching it. What evidence shows a force acted at a distance?
The paper clip began moving before contact happened.
This happens when two objects have the same electric charge
A soccer player kicks a ball. Identify the interaction and explain why.
Contact- the players foot physically touches the ball.
The Moon doesn't touch Earth, yet its motion is affects by Earth. What interaction explains this?
Astronauts on the Moon experience less gravitational force than on Earth. What does this tell you about gravitational interactions?
Their strength can differ depending on the objects involved/ distance between them
Two magnets repel before touching. What does this demonstrate about magnetic forces?
They can exert a pushing force across a distance
A charge balloon causes a student's hair to move toward it before touching. What observation is evidence of an electric interaction?
The hair moves before physical contact happens.
A basketball hits the floor and bounces upward? Is the force from the floor contact or non-contact? Defend your answer.
Contact, the floor and the ball physically touch during the interaction
A paper clip moves toward a magnet from 3 cm away but not from farther away. What can you infer?
The magnetic interaction becomes weaker as distance increases
Two objects are moved further apart. Predict how their gravitational interaction changes and explain.
The gravitational force becomes weaker as distance increases.
A student says, "Magnets only pull objects toward them." Use evidence to correct the claim.
Incorrect. Magnets can attract OR repel. Like poles repel, opposite poles attract
A charge object attracts another object without touching it. How could you prove that the movement was causes by a non-contact interaction?
Show that the second object begins moving while there is still space between the objects
A student says," if objects don't touch, they can't affect each other's motion" Give two examples that disprove the claim.
Examples: Gravity, magnetic forces, or electric forces acting across a distance.
CER CHALLENGE A magnet causes an object to move without touching it. Make a claim and give evidence showing that a force acted at a distance.
Claim: Magnetic forces can act at a distance
Evidence: The object changed motion before the magnet physically touched it.
Reasoning: A change in motion indicates a force acted, and because there was no contact, the magnetic force acted across a distance.