Which of the following describes an action-reaction pair?

A. The Sun pulls on Earth, and Earth pulls on the Moon.
B. You push up on a barbell, and the barbell pushes down on you.
C. You push down on a desk, and the desk pushes down on the ground.
D. A man pushes a car forward, and the car pulls the man forward.

Question

Which of the following describes an action-reaction pair?

 		A.	The Sun pulls on Earth, and Earth pulls on the Moon.
 		B.	You push up on a barbell, and the barbell pushes down on you.
 		C.	You push down on a desk, and the desk pushes down on the ground.
 		D.	A man pushes a car forward, and the car pulls the man forward.

anonymous · Answer

B

anonymous · Answer

B. because the barbell bushes back on you.

anonymous · Answer

Newton's 3rd law:  For every action there is an equal and opposite reaction.

anonymous · Answer

B

This is because of Newton's second law. For every reaction, there is an opposite and equal reaction.

You can think of it like this: If you placed a bowling ball on the ground, why doesn't it just plummet to the core of the earth? The reason is that the ground is pushing upwards with the same force that the bowling ball is pushing down onto the earth.


        ()↓ 9.8N 
----↑ 9.8N--------

anonymous · Answer

Same reason that if you lean against a wall, the wall doesn't just crumble and you fall into the next room. If you push onto a wall with a force of 20N, the wall is pushing back onto you with a force of 20N. It is until the wall can not match your force that it then breaks.