$A$ force of $(4\hat i + \hat j + 3\hat k) \, N$ acts on a body,causing its displacement from $(3\hat i + 2\hat j - 6\hat k) \, m$ to $(14\hat i + 13\hat j + 9\hat k) \, m$. Calculate the work done in $J$.

If a force $\vec F = 4\hat i + 5\hat j$ causes a displacement $\vec s = 3\hat i + 6\hat k$,the work done is:

$A$ 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

$A$ body of mass $m$ is moving in a circle of radius $r$ with a constant speed $u$. The force on the body is $mv^2/r$ and is directed towards the centre. What is the work done by this force in moving the body over half the circumference of the circle?

$A$ particle moves from position $3\hat i + 2\hat j - 6\hat k$ to $14\hat i + 13\hat j + 9\hat k$ due to a uniform force of $(4\hat i + \hat j + 3\hat k) \, N$. If the displacement is in meters,the work done will be ......... $J$.

$A$ 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: