51. A body of mass 2 kg is thrown upward with initial velocity of 20 m/s. After 2 seconds, its kinetic energy will be : (g = 10 m/s2) A.0 J B.200 J C.400 J D.100 J
Option A Solution: We will use the following equation of motion to get the final velocity after 2 seconds. V = u - gt U = 20 m/s g = 10 t = 2 V = 20 - 2 × 10 V = 20 - 20 V = 0 K.E = 1/2mv² m = 2 v = 0 K.E = 0.5 × 0 × 2 = 0
