Newton's Third Law: Confused by Box & Ground Forces

[ProPM]

So, I'm a bit confused... As an example, let's use a box resting on the floor:

I understand the first pair of forces well: Earth pushes the box down with force W, box pulls the Earth up with a force of magnitude W.

Now, the other pair of forces are the normal forces, which my teacher told me, is due to the fact that, when the box stands on the ground, it compresses the molecules right below, and therefore, the reaction force is repulsion from the molecules under the compressed ones.

What confuses me in my book is that it says that the ground pushes up on the box with a force N and that, therefore, the box reacts by pushing down. But, from my teacher explanation I thought that the box pushed the the ground with force N and the ground reacted. Both statements are correct?

My last doubt is: If the box is standing on the ground and not moving, than the force N upwards from the ground on the box must be equal to the box's weight, and, consequently, so that the Earth does not move, the force N exerted on the ground by the box must be equal the force of the box pulling up on the Earth W in magnitude, right?

Thanks and sorry for the long text, I just wanted to make sure I got my doubt across clearly.

 

[Stochastic13]

Dude, you're thinking too much. Box it pressing on the Earth with its weight that is mass of the box times gravity, the Earth is pushing back on the box with the normal force that equals the weight of the box. That's it.

 

[Stochastic13]

The pull of the box on the Earth is negligible and thus useless for any calculations that you can carry out, so don't worry about that.

 

[tiny-tim]

Hi ProPM!

… Both statements are correct?

Both statements are correct.

My last doubt is: If the box is standing on the ground and not moving, than the force N upwards from the ground on the box must be equal to the box's weight, and, consequently, so that the Earth does not move, the force N exerted on the ground by the box must be equal the force of the box pulling up on the Earth W in magnitude, right?

Right.

 

[ProPM]

Thanks