Question

We know that in the universe every two object exerts force on one another. Then why an apple falls towards the earth and not the earth comes towards the apple?? Also the force applied by both are also same.

Answer 1

The force on the apple due to the earth is exactly equal to the force on the earth due to the apple. Now, this force accelerate the bodies and cause motion. We know, F = ma or, a = F/m. Which implies the acceleration is inversely proportional to the mass. The mass of earth is so huge that the acceleration of the earth, due to the force by the apple, is negligible. On the other hand, the mass of the apple is small so the acceleration of the apple is observable and we all know its value is 9.81 ms^-2.