$A$ stone is dropped from the top of a tower. Its speed after it has fallen $20 \, m$ is (Take $g = 10 \, m s^{-2}$): (in $, m s^{-1}$)

At which of the following locations is the value of $g$ maximum?

If the density of a planet is doubled without changing its radius,how does $g$ on the planet change?

The graph below shows the change of ice to steam. Observe the change of state from ice to water and water to steam,and write two inferences that can be drawn from this graph about these changes of state.

$(i)$ Is the acceleration due to gravity of earth '$g$' always a constant at every place? Discuss.
$(ii)$ During a free fall,will heavier objects accelerate more than lighter ones? Give reason for your answer.

$(a)$ The weight of a man on the surface of the earth is $392 \, N$. Find his mass. $(g = 9.8 \, m s^{-2})$
$(b)$ If the man were taken to the moon,what would be:
$(i)$ his mass and
$(ii)$ his weight?
$(iii)$ Calculate the acceleration due to gravity on the moon.