$A$ 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 $t_0$. According to observer $B$,the net work done on the block is

$A$ particle of mass $m$ moves along a circular path of radius $r$ under the influence of a centripetal force $F$. What is the work done when the particle moves along a semi-circular path?

$A$ force $F = (5\hat i + 3\hat j) \, N$ is applied to a particle,which displaces it from its origin to the point $r = (2\hat i - 1\hat j) \, m$. The work done on the particle is:

Which of the following is a scalar quantity?

$A$ uniform force of $(3\hat i + \hat j) \text{ N}$ acts on a particle of mass $2 \text{ kg}$. The particle is displaced from position $(2\hat i + \hat k) \text{ m}$ to position $(4\hat i + 3\hat j - \hat k) \text{ m}$. The work done by the force on the particle is ............. $J$.

In the figure shown,all the surfaces are frictionless,and the mass of the block $m$ is $1\,kg$. The block and wedge are held initially at rest. Now,the wedge is given a horizontal acceleration of $5\,m/s^2$ by applying a force on the wedge,such that the block does not slip on the wedge. Then,the work done by the normal force in the ground frame on the block in $2\,sec$ is ............... $J$.