If an object is dropped from rest onto the surface of an unknown planet from a height of 50 m and it reaches the ground in 2 s, what is the acceleration due to gravity on this planet?

A body falls freely under the influence of gravity (g = 9.8 m/s2) from a height of 200 m. Find its velocity when it strikes the ground.

A block of mass 20 kg is dropped from the top of a building of height 200 m. What will be the velocity with which the block hits the ground? (Take g = 10 m/s2)