A block moving horizontally on a smooth surface with a speed of $40\, {m} / {s}$ splits into two parts with masses in the ratio of $1: 2$. If the smaller part moves at $60\, {m} / {s}$ in the same direction, then the fractional change in kinetic energy is :-
$\frac{1}{3}$
$\frac{2}{3}$
$\frac{1}{8}$
$\frac{1}{4}$
The kinetic energy $k$ of a particle moving along a circle of radius $R$ depends on the distance covered $s$ as $k = a{s^2}$ where $a$ is a constant. The force acting on the particle is
A shell of mass $200\, gm$ is ejected from a gun of mass $4\, kg$ by an explosion that generates $1.05\, kJ$ of energy. The initial velocity of the shell is .............. $\mathrm{ms}^{-1}$
A rifle bullet loses $1/20^{th}$ of its velocity in passing through a wooden plank. The least number of planks required to stop the bullet is :-
A rifle bullet loses $1/20th$ of its velocity in passing through a plank. The least number of such planks required just to stop the bullet is
Equal force $F ( > mg)$ is applied to string in all the $3$ cases. Starting from rest, the point of application of force moves a distance of $2 m$ down in all cases. In which case the block has maximum kinetic energy?