Question

A body of mass 100kg is released from the a height of 200m. With what energy does the body strike the ground level (take g=30m/s²)

Answer 1

15t^2 = 200

using that t, v = 30t
KE = 1/2 mv^2 = 1/2 * 100 * (30t)^2
= 50 * 900 (200/15) = 600,000 J

or, if you remember,
v^2 = 2as, so
KE = mv^2 = 100*200*30 = 600,000 J