A dumbbell consisting of two masses $m$ each, connected by a light rigid rod of length $l$, falls on two pads of equal height, one steel and the other brass through a height $h$. The coefficient of restitution are $e_1$ and $e_2$ ($e_1 < e_2$). To what maximum height will the centre of mass of the dumbbell rise after bouncing of the pads?
$\frac{h}{e_1 + e_2}$
$(e_1 + e_2)^2 \frac{h}{4}$
$\frac{e_1^2 + e_2^2}{4}\times h$
$\frac{4h}{e_1^2 + e_2^2}$
Two solid rubber balls $A$ and $B$ having masses $200$ and $400\, gm$ respectively are moving in opposite directions with velocity of $A$ equal to $0.3 \,m/s$. After collision the two balls come to rest, then the velocity of $B$ is .............. $\mathrm{m} / \mathrm{s} $
A bullet of mass $0.012\;kg$ and hortzontal speed $70\; m s ^{-1}$ strikes a block of wood of mass $0.4\; kg$ and instantly comes to rest with respect to the block. The block is suspended from the celling by means of thin wires. Calculate the height to which the block rises. Also, estimate the amount of heat produced in the block.
Two identical balls $A$ and $B$ are released from the positions shown in figure. They collide elastically on horizontal portion $MN$. The ratio of the height attained by $A$ and $B$ after collision will be: (neglect friction)
A light particle moving horizontally with a speed $v_1$ strikes a very heavy block moving in the same direction with a speed $v_2$. The collision is elastic. After the collision, the velocity of particle is :-
Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : Body $'P'$ having mass $M$ moving with speed $'u'$ has head-on collision elastically with another body $'Q'$ having mass $'m'$ initially at rest. If $m< < M,$ body $'Q'$ will have a maximum speed equal to $'2u'$ after collision.
Reason $R$ : During elastic collision, the momentum and kinetic energy are both conserved.
In the light of the above statements, choose the most appropriate answer from the options given below: