$A$ body of mass $m$ kg is lifted by a man to a height of one metre in $30\, s$. Another man lifts the same mass to the same height in $60\, s$. The work done by them are in the ratio:

If force and displacement of a particle in the direction of force are doubled,the work done would be:

$A$ force of $5 \, N$ acts on a $15 \, kg$ body initially at rest. The work done by the force during the first second of motion of the body is

$A$ force $\vec F = 2\hat i - 3\hat j + 7\hat k \text{ (N)}$ acts on a particle which undergoes a displacement of $\vec S = 7\hat i + 3\hat j - 2\hat k \text{ (m)}$. Calculate the work done by the force in $J$.

$A$ $50\,kg$ man with a $20\,kg$ load on his head climbs up $20$ steps of $0.25\,m$ height each. The work done in climbing is......$J$

Show that a force that does no work must be a velocity-dependent force.