Is this possible? To speed up, slow down, or change earth rotation by walking?

Question

If the planet was all land, with no oceans and flat. Could we change the speed or direction of the rotation, if everyone on this planet. Stood side by side in single file lines, and walked in one direction?

or
what if we made all the fans or anytype of blowers face a certain direction, could that change the spin?

Answer 1

Best Answer - Chosen by Voters

Technically yes.
At any given instant all the mass on the earth has some total angular momentum. This total must be constant in time. So if someone begins walking in the same direction as the earth's rotation that would add to the angular momentum of the total, which is not allowed. So to compensate, the rest of the earth would reduce its rotation speed. Conversely if someone walks the other way the earth has to speed up.

Certainly the effect would be greatly enhanced if everyone did it in sync.

But alas, the angular momentum is also proportional to the mass that's spinning. All the people on earth have a miniscule mass compared to the rest of the earth. So any effect would be so small as to be immeasurable.
Would be like asking how much work your arm muscles have to do to hold up a flea in your hand.