Question

It is seen that falling apple is attracted towards the Earth. We all know that apple will also exert an equal and opposite force on the Earth. If so, we don’t see Earth moving towards the apple, why?

• A. The mass of apple is negligibly small compared to that of the Earth.
• B. The acceleration produced by the apple on the Earth would be negligible.
• C. Cannot be determined with the given information
• D. The force acting on both that is on apple and Earth is equal.

Answer 1

Answer: (A), (B), (D)

The correct options are
A The mass of apple is negligibly small compared to that of the Earth.
B The acceleration produced by the apple on the Earth would be negligible.
D The force acting on both that is on apple and Earth is equal.

From Newton’s $2^{nd}$ law, we know that acceleration is inversely proportional to mass, i.e.,
$F=ma$
where, $a$ is the acceleration of an object and $m$ is the mass of an object.
or, Acceleration $a=\frac{F}{m}$
The mass of apple is negligibly small as compared to that of the Earth. So, for same gravitational force, acceleration of the Earth is very small. Thus, Earth will not move, whereas apple will have considerable acceleration (less mass), which brings it down. We can extend the same argument for why the earth does not move towards the moon.