Question

Work done by gravity on falling ball in first second and third second

Answer 1

Work done = Force • Displacement
= mg • displacement

using, d = Vo + (1/2)(a)(t)^2

= (mg)(1/2)(a)(t)^2 (initial velocity = 0)
= (1/2)m(gt)^2

Work done in first second will be
= (1/2)m(g)^2 Joules

Now work done in third second
= Work done in 3 seconds - work done in 2 seconds
= (1/2)m(g3)^2 - (1/2)m(g2)^2
=(5/2)m(g)^2 Joules