Newton's third law and a box push

In summary, the person is able to move a box because the box and the person have equal but opposite forces acting on them. The Earth helps to accelerate the box so that it barely moves.
  • #1
mk876
6
0

Homework Statement



I just don't understand how to describe how, if a person pushes on a box and the box exerts an exactly equal but opposite force on the person that the person is still able to move the box...

Homework Equations



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The Attempt at a Solution



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  • #2
What about the feet of that person ?
 
  • #3
So the feet of the person are meant to absorb the force of the box?
 
  • #4
So what is there beneath the feet of the person ?

Maybe if you drew a very simple drawing of the situation it will help greatly.
 
  • #5
The earth.

I drew a picture and the forces are the force of the person on the box, the force of the box on the person, the force of the person on the Earth and the force of the Earth on the person (not including the earth/box forces).

So the forces acting on the person are that of the box and that of the earth...
 
  • #6
mk876 said:
So the forces acting on the person are that of the box and that of the earth...

Ok, but it's more correct the other way round: the forces acting on the box and on the Earth are the same that those the person exerts.
 
  • #7
:( I'm confused.
 
  • #8
mk876 said:
:( I'm confused.

Don't worry. I think you already got the situation correctly.
 
  • #9
Ohh so are you saying the Earth will absorb the force of the box and so the person is able to move it?
 
  • #10
mk876 said:
Ohh so are you saying the Earth will absorb the force of the box and so the person is able to move it?

Think about a slightly different situation.

The person acts like a spring, pushing with a force F at one end and with the same force F at the other end.
The Earth and the box are then pushed by those Forces.
Since the Earth is very big, it will barely move at all.
But, the Earth is accelerated as well by a very very small quantity.

So you have 2 pairs of forces.
At one end of the spring, the earth-spring (action-reaction), on the other side spring-box (action reaction).
 
  • #11
Ohhh alright I think I understand a lot better now. Thanks for helping me out :D
 

Related to Newton's third law and a box push

What is Newton's third law?

Newton's third law states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object will exert a force back on the first object that is equal in magnitude and opposite in direction.

How does Newton's third law apply to a box push?

In a box push, the person pushing the box exerts a force on the box, causing it to move. However, the box also exerts an equal and opposite force back on the person, pushing them in the opposite direction. This is an example of Newton's third law in action.

Why is it important to understand Newton's third law when pushing a box?

Understanding Newton's third law is important when pushing a box because it helps us predict and understand the motion of objects. It also reminds us that every action has an equal and opposite reaction, so we must consider both forces when pushing or moving objects.

Does Newton's third law only apply to pushing objects?

No, Newton's third law applies to all interactions between objects. It is a fundamental law of physics that describes the relationship between forces and motion.

Can Newton's third law be violated?

No, Newton's third law is a fundamental law of physics and has been extensively tested and proven. It cannot be violated in any scenario.

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