Question

The claim is made that forces can exist between objects, even when the objects are not in contact.

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Which THREE statements BEST support the claim?

A.
If a ball is thrown up in the air, a gravitational field will develop between the Earth and the ball and gravitational force will pull the ball closer to the Earth.

B.
If two electrically neutral objects are rubbed together, an electric field will develop between them, and the electric force will pull the objects closer together.

C.
If a ball is thrown up in the air, an electric field will develop between the ball and the Earth, and the gravitational force will pull the ball and the Earth closer together.

D.
If two magnets are placed with their opposite poles facing each other, a magnetic field will develop between the magnets and the force created will pull them together.

E.
If two magnets are placed with their opposite poles facing each other, an electric field will develop between the magnets and the electric force will pull the magnets together.

Answer 1

A, B, and D.

- A: Gravity acts at a distance via a gravitational field between the Earth and the ball, so the Earth pulls the ball without contact.
- B: Rubbing can transfer charge so the objects develop an electric field and attract; this is an example of a non-contact electric force.
- D: Opposite poles of magnets produce a magnetic field and a magnetic force that pulls them together without contact.

C and E are incorrect because they confuse fields (static magnets produce magnetic, not electric, fields) or state fields that do not generally arise in the situations described.