Question

Newton's law states that a particle attracts every other particle in the universe using a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
If you throw a ball up in the air, it falls down because of gravitational force of earth. Why doesn't the earth move up if an equal force is exerted on it by the ball ?

• A. The law is applicable only to bodies of small mass.
• B. The law is applicable to only bodies with small volume.
• C. The force exerted by the ball is too small to move the earth.
• D. None of the above.

Answer 1

Answer: (C)

The force exerted by the ball is too small to move the earth.

$F=\frac{G{M}_1{M}_2}{R^2}$

$\therefore$ force $\propto$ Mass

Since the mass of the ball is very small as compared to that of the earth force exerted by the ball is far less than the force exerted by earth.Thus the earth doesn't move towards the ball.