$A$ 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 $, m s^{-1}$)

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

$A$ 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?

State whether the following statement is True or False:
The acceleration due to gravity $g$ is given by the formula $g = GM/R^2$,where symbols have their usual meanings.

Consider Earth to be a homogeneous sphere. Scientist $A$ goes deep down in a mine and scientist $B$ goes high up in a balloon. The acceleration due to gravity as measured by:

An object is placed one by one in three liquids having different densities. The object floats with $\frac{1}{9}$, $\frac{2}{11}$, and $\frac{3}{7}$ parts of its volume outside the liquid surface in liquids of densities $d_1$, $d_2$, and $d_3$ respectively. Which of the following statements is correct?