Define free fall.

$A$ 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? $(g=10\, m s^{-2})$

An iron sphere of mass $10 \, kg$ has the same diameter as an aluminium sphere of mass $3.5 \, kg$. Both spheres are dropped simultaneously from a tower. When they are $10 \, m$ above the ground,they have the same

An object is dropped from rest at a height of $150 \, m$ and simultaneously another object is dropped from rest at a height of $100 \, m$. What is the difference in their heights after $2 \, s$ if both objects drop with the same acceleration? How does the difference in heights vary with time?

$A$ stone is dropped from a cliff. Its speed after it has fallen $100 \,m$ is: (in $, m s^{-1}$)

What is meant by acceleration due to gravity? Suppose a planet exists whose mass and radius both are half of that of Earth. Calculate the acceleration due to gravity on the surface of this planet.