Does an Apple’s Gravity Influence Earth’s Movement?

[mtasquared]

When an apple falls to the ground does it not exert some gravity of it's own on the Earth and thus shortening the distance it falls? Why is it always assumed the Earth does not itself move in physics problems?

 

[Doc Al]

When an apple falls to the ground does it not exert some gravity of it's own on the Earth and thus shortening the distance it falls?

Sure.

Why is it always assumed the Earth does not itself move in physics problems?

Estimate the Earth's acceleration due to the apple's gravitational pull. Then you'll see why it's ignored.

 

[DocZaius]

When an apple falls to the ground does it not exert some gravity of it's own on the Earth and thus shortening the distance it falls? Why is it always assumed the Earth does not itself move in physics problems?

The idea of ignoring negligible calculations is to make it easier for students who are introduced to these concepts to make the calculations. However I think it should still be said to the students that the apple is causing the Earth to undergo a very very very small acceleration, so that they can be reminded that forces affect both objects.

 

[mtasquared]

Thanks for replying!