Question

Assertion: Gravitational force on an object on the moon is one-sixth that on the earth.
Reason: The law of gravitation is the same on both the moon and the earth.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (B)

Newton's law of gravitation says that the force acting between two bodies is given by, $F\propto \frac{Mm}{R^2}=K\frac{Mm}{R^2}$ , where $M\text{and}m$ are the mass of the different bodies, $R$ is the distance between them and $K$ is the proportionality constant.
From the above formula, we can see force depends on mass as well distance between them. In the case of gravitational force $M\text{and}R$ are the mass and radius of planet. We know that earth is massive compare to the moon and its radius is also bigger than the moon.
Then, the gravitational force due to earth is $6$ times more than the moon.