Why does a skateboard move backward when you push on it, but the Earth does not?

[LindaJalie]

Use Newton's to explain :

When you take a step, you push down and back on the Earth and the Earth pushes up and forward on you. When you step on a skateboeard, the skateboard moves backward as you push down and back. Why does the skateboard move backward while the Earth does not even if the force is the same?

 

[DaveC426913]

What makes you think the Earth doesn't move?

How much more massive is the Earth than a skateboard?

 

[LindaJalie]

It does. But the Earth masses as much as 6 million billion billion skateboards. It moves one 6 million billion billionths as much.

Could you explain why ? I need details for this answer

 

[DaveC426913]

Sorry. I went back and edited my answer once I realized that this is a homework question.

If you are studying Newton, you are familiar with F=ma?

 

[LindaJalie]

Sorry. I went back and edited my answer once I realized that this is a homework question.

If you are studying Newton, you are familiar with F=ma?

I need to explain details for this question

 

[Simon Bridge]

Could you explain why ? I need details for this answer.
... I need to explain details for this question

It would defeat the point of the exercise if any of us provided you with a detailed answer.
You have to provide the details yourself.

But the start has been given to you. The questions are there to guide you.
If you try to walk on a wheeled platform, i.e. the skateboard, the platform goes backwards over the ground ... why does it do that? Can you tell us in your own words?

If you walk on the Earth ... you have to push on the Earth. The Earth is just another mass ... what happens to masses when you push on them?