Looking for classes? Ksquare Career Institute, Bengaluru →
Conservation of energy
Concepts tested here
- Energy loss in collision
All Questions
2015 AIPMT-II 1 question
-
A ball is thrown vertically downwards from a height of 20 m with an initial velocity $u_0$. It collides with the ground, loses 50 percent of its energy in collision and rebounds to the same height. The initial velocity $u_0$ is: (Take g = 10 $ms^{-2}$)Rebound speed: $v = \sqrt{2gh} = \sqrt{2\times10\times20} = 20$ m/s
Energy just after rebound: $E = \frac{1}{2}mv^2 = 200m$
50% is lost in the collision, so the energy just before collision = 400m.
$\frac{1}{2}mu_0^2 + mgh = 400m \Rightarrow \frac{1}{2}u_0^2 + 200 = 400 \Rightarrow u_0 = 20$ m/s