Question

6) A ball of mass 5kg is dropped from a tower of height 40m. What is its kinetic energy half way down? (g = 10 m/s2)

Answer 1

At height 40 m, the ball have potential energy,
PE = mgh = 5×10×40 = 2000 J
KE =0
Total energy, TE = PE +KE = 2000 J
At half way down PE = mgh/2 = 1000 J
Total energy is always constant
TE =PE + KE
⇒KE = 2000 - 1000 = 1000 J
One can find velocity at this position by applying (1/2 )×mv² = 1000 J