Question

an object is falling freely from rest of height of 65m above the ground what is the height of the object from the ground in meter when it reaches velocity of 20m/s?

Answer 1

v = 9.8t, so it takes 20/9.8 = 2.04 seconds to achieve that speed.

Since h = 65-4.9t^2,
plug in 2.04 to get h at that time.