Is it possible to push Earth down more than you weigh?

[deakin22]

Here's a question that I'm pretty sure I know the answer to, but I was talking with a friend earlier and it just made me second guess...

So let's say

You are a bodybuilder. One day you decide to get on your knees (in a stationary position) and try and push the Earth down. Is the amount of force you exert entirely dependent on how much you weigh or does it matter if you can bench press 3/4/500 pounds? Does muscular strength even matter in this scenario?

 

[davenn]

have a look at Newton's laws of motion, particularly Law III
... To every action there is always an equal and opposite reaction: or the forces of two bodies on each other are always equal and are directed in opposite ...

Dave

 

[Nugatory]

Here's a question that I'm pretty sure I know the answer to, but I was talking with a friend earlier and it just made me second guess...

So let's say

You are a bodybuilder. One day you decide to get on your knees (in a stationary position) and try and push the Earth down. Is the amount of force you exert entirely dependent on how much you weigh or does it matter if you can bench press 3/4/500 pounds? Does muscular strength even matter in this scenario?

If you want to push the Earth with a force greater than your weight, you can jump. While you are accelerating your body upwards, the force on your body is greater than just your weight. Or you could throw a heavy weight straight up into the air - while you're accelerating it upwards the force you are exerting on it must be greater than its weight, and therefore the equal and opposite force on the Earth will also be greater.

You can see this effect pretty clearly by jumping up and down on a bathroom scale (if you can find one that won't break under the abuse).