Question 333: Centre of Mass and Rotational Motion

Question

A ball kept at $$20 \mathrm{~m}$$ height falls freely in vertically downward direction and hits the ground. The coefficient of restitution is 0.4. Velocity of the ball first rebound is $$\left[\mathrm{g}=10 \mathrm{~ms}^{-2}\right]$$

Accepted Answer

$$\begin{aligned}
& v^2=0+2 g h \quad \ldots .\left(\because v^2-u^2=2 g hight) \
& v^2=2 	imes 10 	imes 20=400 \
	herefore \quad & v=20 \mathrm{~m} / \mathrm{s} \
& e=\frac{u}{v}
\end{aligned}$$
$$	herefore \quad$$ The velocity of the body after the first rebound is
$$\begin{aligned}
& \mathrm{u}=0.4 	imes 20 \
& \mathrm{u}=8 \mathrm{~m} / \mathrm{s}
\end{aligned}$$

Answer

$$4 \mathrm{~ms}^{-1}$$

Answer

$$8 \mathrm{~ms}^{-1}$$

Answer

$$12 \mathrm{~ms}^{-1}$$

Answer

$$16 \mathrm{~ms}^{-1}$$

Centre of Mass and Rotational Motion

A ball kept at $20 \mathrm{~m} height falls freely in vertically downward direction and hits the ground. The coefficient of restitution is 0.4. Velocity of the ball first rebound is \left[\mathrm{g}=10 \mathrm{~ms}^{-2}\right]

Choose the correct answer: