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

$A$ block of mass $m$ is kept in an elevator which starts moving downward with an acceleration $a$ as shown in the figure. The block is observed by two observers $A$ and $B$ for a time interval $t_0$. The observer $B$ (who is on the ground) finds that the work done by gravity on the block is:

$A$ body of mass $10\, kg$ is dropped to the ground from a height of $10\, m$. The work done by the gravitational force is ............. $J$ $(g = 9.8\, m/s^2)$.

$A$ body,acted upon by a force of $50 \, N$,is displaced through a distance of $10 \, m$ in a direction making an angle of $60^\circ$ with the force. The work done by the force is .......... $J$.

$A$ force $\vec F = (5\hat i + 3\hat j + 2\hat k) \, N$ is applied to a particle which displaces it from its origin to the point $\vec r = (2\hat i - \hat j) \, m$. The work done on the particle in joules is

$A$ horizontal force of $5 \,N$ is required to maintain a velocity of $2 \,m/s$ for a block of $10 \,kg$ mass sliding over a rough surface. The work done by this force in one minute is $J$.