Help me with Newton's 3rd Law of Motion

[galiciadba]

Homework Statement

Hi, this is not a homework but I've had this question stuck my in head for so long and I just can't understand what my teacher's explanation.

Okay here goes...
According to Newton's 3rd law of motion, "for every action, there is an equal and opposite reaction", then how are we able to move? Isn't there an opposing force in every action? If I exert a force of 10N, isn't there an equal and opposite reaction of 10N that is supposed to balance out the force? If so, how are we able to move at all?

Homework Equations

N/A

The Attempt at a Solution

My teachers always tell me something about "acting on a body" which I have no idea what it means at all.

Thanks! I just sat for my paper and lucky me, a similar question came out. Just my luck.

 

[Disconnected]

Hey, galiciadba. Welcome to PF.

When you push on a ball with your hand, you feel the contact, correct? This is the normal reaction force of the ball pushing on your hand. It is trying to move you, but your feet are in contact with the ground and the friction between your feet and the ground stops you from moving backwards. But the ball, lacking such friction, does move.

Now imagine that the ball is a refrigerator fixed in place, and that you are on an ice rink. Now when you push, in exactly the same way you move, not the fridge.

In each case, the forces between you and the object are the same. If you push at 5N, the normal reaction force is 5N, otherwise your hand would just move through the ball.

Image two magnets on a very smooth ice rink. They will both move towards each other, both feel the same attraction. There is an attractive force acting on magnet A working due to magnet B, and an attractive force equal in magnitude but opposite in direction[\i] acting on magnet B due to magnet A.

I hope that helped clarify, though I fear I worded it horrendously...

Edit to add: If that didn't clarify, feel free to ask more questions.

 

[ashishsinghal]

Lets say you are pulling a heavy box by a string on a frictionless surface. You will apply force on the block. Hence block will move towards you. According to the third law the block also applied force on you towards itself. Hence you will move towards it. Simple. Your teacher is right about "acting on a body".

your force "acts: on the block which makes it move and force on block "acts" on you, so you move. We would not have moved if both the forces acted on the same object but it is not so as one acts on you and the other on the block.
Hope it helps!