Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: The location of an object in a frame of reference is called position.

A: The location of an object in a frame of reference is called what?
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Q: Zero is the net force acting on an object when two equal forces are applied from opposite directions.

A: What is the net force acting on an object when two equal forces are applied from opposite directions?
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Q: A(n) electroscope is used to study charge.

A:
What device is used to study charge?
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