An astronaut accidentally gets separated from his small spaceship accelerating in interstellar space at a constant rate of $100 \; m/s^2$. What is the acceleration of the astronaut the instant after he is outside the spaceship (in $; m/s^2$)? (Assume that there are no nearby stars to exert gravitational force on him.)

$A$ man getting down from a running bus falls forward because:

$A$ stone tied to the end of a string is whirled in a circular path. Why does the stone move in the direction of the tangent at that point when the string breaks?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A:$ An electric fan continues to rotate for some time after the current is switched off.
Reason $R:$ The fan continues to rotate due to inertia of motion.
In the light of the above statements,choose the most appropriate answer from the options given below.

$A$ body of mass $2 \, kg$ is sliding with a constant velocity of $4 \, m/s$ on a frictionless horizontal table. The force required to keep the body moving with the same velocity is .......... $N$.

Write and explain Newton's first law of motion.