The force of attraction of the earth on an apple is of the same magnitude as the force of attraction of the apple on the earth, yet the apple moves towards the earth, but the earth does not move towards the apple. Why?

Explanation

Suppose the earth of mass M attracts an apple of mass m with a force F towards it. As per the law of gravitation, the apple also attracts the earth with the same force F towards it.
Acceleration of the apple due to the earth.s pull
`=("force on apple")/("mass of apple")=F/m`
Acceleration of the earth due to attraction of the apple
`=("force on the earth ")/("mass of the earth ")=F/M`
Hence, `("acceleration of the apple")/("acceleration of the earth")= (F/m)/(F/M)=M/m`
As the mass of the apple is negligible compared to that of the earth `M/mgt gt 1`.
That is to say, acceleration of the apple `gt gt` acceleration of the earth. Practically, the apple moves towards the earth. Motion of the earth towards the apple is too small to be noticed.