Answer to Question #86475 in Mechanics | Relativity for Gift apuye

Question

A force of 9.0N is applied to a body at rest on a smooth horizontal surface. If the body has a mass of 18.0kg and it moves in the direction of the force,find the work done in the first four seconds and the fourth second

Answer 1

The body acceleration a = F/m, then its velocity v = at = Ft/m, and kinetic energy K = mv²/2 = (Ft)²/2m. The work done A equals to K, so A₁ = (9*4)²/2*18 = 36 (J), A₂ = (9*4)²/2*18 - (9*3)²/2*18 = 15.8 (J).

   Finally, A₁ = 36 J, A₂ = 15.8 J.