The work done by a force $\vec F\, = \,( – \,6{x^3}\,\hat i)N$ , in displacing a particle from $x = 4\,m$ to $x = -\,2\,m$ is ………….. $\mathrm{J}$

A ball is dropped from height $h$ on a plane. If the coefficient of restitution of the plane is $e$ and if ball hits ground two times, the height upto which it reaches after two jumps, will be

A particle of mass $M$ is moving in a horizontal circle ofradius $R$ with uniform speed $v$. When it moves from one point to a diametrically opposite point, its
 

Two identical particles are moving with same velocity $v$ as shown in figure. If the  collision is completely inelastic then

A body of mass $2\,kg$ makes an elastic collision with another body at rest and continues to move in the original direction with one fourth of its original speed, The mass of the second body which collides with the first body is …………… $\mathrm{kg}$