Embibe Experts Solutions for Chapter: Gravitation, Exercise 8: Exercise (Assertion & Reason)

Assertion : A person feels weightlessness in an artificial satellite of the earth. However a person on the moon (natural satellite) feels his weight.
Reason : Artificial satellite is a freely falling body and on the moon surface, the weight is mainly due to moon’s gravitational attraction.

Assertion : The gravitational field of moon is much less than that of earth.
Reason : Gravitational field of a given mass ($M$) depends upon $\frac{M}{r^2}$, which is smaller for moon.

Assertion : In keplar’s law conservation of angular momentum does not take place.
Reason : Gravitation force acting between earth and the sun is perpendicular to line joining them.

Assertion: On decreasing the distance between two masses potential energy increases.
Reason : Potential energy $U=\frac{GMm}{r}$.

Assertion : A body falling freely under the force of gravity has constant acceleration (9.81 m/sec²).
Reason : Earth attracts every body towards its centre by the same force.

Assertion : A body kept inside a spherical shell does not experience any gravitational force.
Reason : The body inside a spherical shell is protected from the gravitational attraction of bodies outside the shell.

Assertion : If value of acceleration due to gravity of a planet is lesser than earth then escape velocity from planet is lesser too.
Reason : Escape velocity just depends only on acceleration due to gravity.

Assertion : If gravitational force is proportional to $\frac{1}{R^3}$ then Kepler's second law would not be affected.
Reason : For Keplar’s second law, central nature of force is the only condition.