Question

a stone of mass 0.4 kg is thrown vertically up with a speed of 9.8m/s.find the potential and kinetic energies after half second

Answer 1

KE = 1/2 * m * v^2

KE = 1/2 * 0.4 * 9.8^2 = 19.208 J

PE = mgs

Assuming, the ball was thrown from 0 distance from surface,

s = 9.8 * 0.5 + 1/2 * -10 * 0.5^2 = 3.65 m

PE = 0.4 * 10 * 3.65 = 14.6 J

Please comment if you find anything odd, or have a doubt.