Question

An apple falls from a tree. An insect in the apple finds that the earth is falling towards it with an acceleration g. Who exerts the force needed to accelerate the earth with this acceleration?

Answer 1

• According to Newton’s third law, when an apple is freely falling, the force on the apple due to earth is equal to the force on the earth due to apple. 
• The force is due to gravity, which causes acceleration in the body.
• As the insect is inside the freely falling apple, it feels that the earth is falling towards it with an acceleration ’g’. 
• According to the insect, the acceleration is due to the force on the apple due to the earth. 
• Actually the earth is not falling towards the apple.