The bob of a pendulum is released from a horizontal position A as shown in the figure. If the length of the pendulum is 1 . 5 m , what is the speed with which the bob arrives at the lowermost point B , given that it dissipated 5 % of its initial energy against air resistance?

Step-by-step solution

At the point A the energy of the pendulum is entirely potential energy. At point B, the energy of the pendulum is entirely kinetic energy. It means that as the bob pendulum lowers from A to B, the potential energy is converted into kinetic energy. Thus, at B , KE = PE. But 5 % of the potential energy is dissipated against air resistance. KE at B = 95 %  of   PE   at   A .... (i) ∴       From equation (i), 1 2 m v 2 = 95 100 m g h v 2 = 2 × 95 100 g h = 2 × 95 100 &