A bullet is fired from a rifle. If the rifle recoils freely, then the kinetic energy of the rifle is

The bob of a simple pendulum (mass m and length $ l$) dropped from a horizontal position strikes a block of the same mass elastically placed on a horizontal frictionless table. The K.E. of the block will be

A running man has half the kinetic energy of that of a boy of half of his mass. The man speeds up by $1\,m/s$ so as to have same K.E. as that of the boy. The original speed of the man will be

Two solids $A$ and $B$ of mass $1\, kg$ and $2\, kg$ respectively are moving with equal linear momentum. The ratio of their kinetic energies $(K.E.)_{ A }:( K.E. )_{ B }$ will be $\frac{ A }{1},$ so the value of $A$ will be ..... .

Consider the following two statements
$1.$ Linear momentum of a system of particles is zero
$2.$ Kinetic energy of a system of particles is zeroThen

A particle $A$ is projected vertically upwards. Another particle $B$ is projected at an angle of $45^{\circ}$. Both reach the same height. The ratio of the initial kinetic energy of $A$ to that of $B$ is