A block moving horizontally on a smooth surface with a speed of $40\, {ms}^{-1}$ splits into two equal parts. If one of the parts moves at $60\, {ms}^{-1}$ in the same direction, then the fractional change in the kinetic energy will be $x: 4$ where $x=..... .$
$4$
$10$
$1$
$50$
A bullet is fired from a gun. If the gun recoils freely, the kinetic energy of the gun will be
A ball of mass $2\,kg$ and another of mass $4\,kg$ are dropped together from a $60$ feet tall building. After a fall of $30$ feet each towards earth, their respective kinetic energies will be in the ratio of
At time $t=0$ is particle starts moving along the $x-$axis. If its kinetic energy increases uniformly with time $t$, the net force acting on it must be proportional to
A ball of mass $2\;kg$ and another of mass $4\; kg$ are dropped together from a $60$ feet tall building. After a fall of $30$ feet each towards earth, their respective kinetic energies will be in the ratio of?
A bomb is kept stationary at a point. It suddenly explodes into two fragments of masses $1\, g$ and $3\;g$. The total K.E. of the fragments is $6.4 \times {10^4}J$. What is the K.E. of the smaller fragment