$A$ heavy box of $40\, kg$ is pushed along $20\, m$ by two coolies over a railway platform whose coefficient of friction with the box is $0.4$. The work done by the two coolies is: .................. $J$ (Take $g = 10\, m/s^2$)

$A$ particle moves from position $\vec{r}_1 = 3\hat{i} + 2\hat{j} - 6\hat{k}$ to position $\vec{r}_2 = 14\hat{i} + 13\hat{j} + 9\hat{k}$ under the action of force $\vec{F} = 4\hat{i} + \hat{j} + 3\hat{k} \text{ N}$. The work done will be ............ $\text{J}$.

$A$ body of mass $6\,kg$ is under a force which causes displacement in it given by $S = \frac{t^2}{4}$ metres, where $t$ is time. The work done by the force in $2\,seconds$ is ............... $J$.

$A$ 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:

$A$ block of mass $m$,kept on a horizontal surface,is moved through a distance $s$ by applying a horizontal force $F$ to it. What is the work done by the normal reaction?

$A$ force of magnitude $50\, N$ acting along $\hat{i} + \hat{j} + \hat{k}$ displaces a point mass from $(5, 9, 7)$ to $(4, 8, 6)$. The work done by this force during this displacement is: