A sphere of mass $m $ moving with a constant velocity $u$ hits another stationary sphere of the same mass. If $e$ is the coefficient of restitution, then the ratio of the velocity of two spheres after collision will be
$\frac{{1 - e}}{{1 + e}}$
$\frac{{1 + e}}{{1 - e}}$
$\frac{{e + 1}}{{e - 1}}$
$\frac{{e - 1}}{{e + 1}}{t^2}$
A block having mass $m$ collides with an another stationary block having mass $2\,m$. The lighter block comes to rest after collision. If the velocity of first block is $v$, then the value of coefficient of restitution will must be
An object is dropped from a height $h$ from the ground. Every time it hits the ground it looses $50\%$ of its kinetic energy. The total distance covered as $t \to \infty $ is
In the above question, if another body is at rest, then velocity of the compound body after collision is
Assertion $(A)$: In an elastic collision between two bides, the relative speed of the bodies after collision is equal to the relative speed before the collision.
Reason $(R)$: In elastic collision, the linear momentum of the system is conserved.
$Assertion$ : In an elastic collision of two billiard balls, the total kinetic energy is conserved during the short time of oscillation of the balls (i.e., when they are in contact).
$Reason$ : Energy spent against friction does not follow the law of conservation of energy.