Question

An apple is attracted towards the Earth as a result of the force of gravity. According to Newton's third law, the apple attracts the Earth with an equal and opposite force. The reason why the Earth does not move towards the apple is
1. The mass of apple is very small.
2. The mass of the Earth is very large.
3. The radius of the apple is too small.
4. The radius of the Earth is too lare.

Answer 1

Correct Answer - Option 2 : The mass of the Earth is very large.

The correct answer is option 2) i.e. The mass of the Earth is very large.

CONCEPT:

• The force due to gravity is given by the equation

Force (F) = m × g

Where, F = Force due to the gravity of the Earth, m = Mass of the object on which the force is acting, and g = Acceleration due to gravity of the Earth.

EXPLANATION:

Force on the object of mass "m" due to the Earth (FOE) is given by:

FOE = m × g

⇒ g = FOE/m

• ​The mass of the apple is very small and is inversely proportional to its acceleration.
• Hence, the acceleration produced in the apple is evident enough to see the apple moving towards the Earth.

Force on Earth due to object (FEO) is given by:

FEO = M × a

⇒ a = FEo/M

• The mass of the Earth is very large as compared to the mass of the apple.
• Since acceleration produced on Earth due to the force is inversely proportional to the mass of the Earth (M), the acceleration will be very less and will not be evident enough to see the Earth accelerating towards the apple.

• The mass of the Earth is approximately equal to 6 × 1024 kg.