$A$ man weighs $600\,N$ on Earth. What is his mass? $(g=10\,m s^{-2})$. On the Moon,his weight would be $100\,N$. What is the acceleration due to gravity on the Moon?

$A$ stone is dropped from a height of $20\, m$.
$(a)$ How long will it take to reach the ground?
$(b)$ What will be its speed when it hits the ground? $(g=10\, m s^{-2})$

How does the weight of an object vary with respect to the mass and radius of the Earth? In a hypothetical case,if the diameter of the Earth becomes half of its present value and its mass becomes four times its present value,then how would the weight of any object on the surface of the Earth be affected?

What is the source of centripetal force that a planet requires to revolve around the Sun? On what factors does that force depend?

At the top of its path,a projectile:

$A$ man throws a ball of mass $0.5 \, kg$ vertically upward with a velocity of $25 \, m s^{-1}$. Find: $(a)$ the initial momentum of the ball,$(b)$ the momentum of the ball at the halfway mark of the maximum height. (Given $g = 10 \, m s^{-2}$)