A bullet moving with a speed of $100$ $m{s^{ - 1}}$can just penetrate two planks of equal thickness. Then the number of such planks penetrated by the same bullet when the speed is doubled will be

A body moving with velocity $v$ has momentum and kinetic energy numerically equal. What is the value of $v$ ........$m/s$

An object of mass ' $m$ ' initially at rest on a smooth horizontal plane starts moving under the action of force $F=2 N$. In the process of its linear motion, the angle $\theta$ (as shown in figure) between the direction of force and horizontal varies as $\theta= kx$, where $k$ is a constant and $x$ is the distance covered by the object from its initial position. The expression of kinetic energy of the object will be $E =\frac{ n }{ k } \sin \theta$. The value of $n$ is $.....$

A projectile is fired with $KE$ of $1\,kJ$. If the range is maximum, .......... $J$ is its $KE$ at the highest point.

A cylinder of $10 \,kg$ is sliding in a plane with an initial velocity of $10 \,m/s$. If the coefficient of friction between the surface and cylinder is $0.5$ then before stopping, it will cover. $(g = 10\,\,m/{s^2})$ ........ $m$

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