A stationary particle explodes into two particles of a masses $m_1$ and $m_2$ which move in opposite directions with velocities ${v_1}$ and ${v_2}.$ The ratio of their kinetic energies ${E_1}/{E_2}$ is

The energy required to break one bond in $DNA$ is $10^{-20}\, J.$ This value in $eV$ is nearly

A body of mass $5\; kg$ is moving with a momentum of $10\; kg m / s$. A force of $0.2\; N$ acts on it in the direction of motion of the body for $10\; sec$. Find the increase in its kinetic energy.

A ball is thrown up with a certain velocity at an angle $\theta$ to the horizontal. The kinetic energy $KE$ of the ball varies with horizontal displacement $x$ as

If the kinetic energy of a body is directly proportional to time $t,$ the magnitude of force acting on the body is

$(i)$ directly proportional to $\sqrt t$
$(ii)$  inversely proportional to  $\sqrt t$
$(iii)$ directly proportional to the speed of the body
$(iv)$ inversely proportional to the speed of body

Two bodies of masses $m$ and $4 \,m$ are moving with equal $K.E.$ The ratio of their linear momentums is