System shown in figure is released from rest. Pulley and spring are massless and the friction is absent everywhere. The speed of $5\, kg$ block, when $2\, kg$ block leaves the contact with ground is : (take force constant of the spring $K = 40\, N/m$ and $g = 10\, m/s^2$)
$\sqrt 2\, m / s$
$2\sqrt 2 \,m/s$
$2 \,m/s$
$4\sqrt 2 \,m/s$
Adjacent figure shows the force-displacement graph of a moving body, what is the work done by this force in displacing body from $x = 0$ to $x = 35\,m$ ? ........... $\mathrm{J}$
Work done in time $t$ on a body of mass $m$ which is accelerated from rest to a speed $v$ in time $t_1$ as a function of time $t$ is given by
A 3.628 kg freight car moving along a horizontal rail road spur track at $7.2\; km/hour$ strikes a bumper whose coil springs experiences a maximum compression of $30 \;cm$ in stopping the car. The elastic potential energy of the springs at the instant when they are compressed $15\; cm$ is [2013]
(a) $12.1 \times 10^4\;J$ (b) $121 \times 10^4\;J$ (c) $1.21 \times 10^4\;J$ (d) $1.21 \times 10^4\;J$
A small block of mass $m$ slides along a smooth frictional track as shown in the figure. If it starts from rest at $P$ , velocity of block at point $Q$ is
A body at rest is moved along a horizontal straight line by a machine delivering a constant power. The distance moved by the body in time $t^{\prime}$ is proportional to :