$A$ force of $5 \,N$ acts on a body initially at rest. If the instantaneous power due to the force at the end of the third second $(t=3 \,s)$ is $5 \,W$, then the mass of the body is (in $\,kg$)

$A$ vehicle of mass $m$ starts from rest and accelerates. If the engine delivers a constant power $p$,what is the velocity of the vehicle at time $t$?

$A$ pump is used to lift $7200 \ kg$ of water per hour from a depth of $100 \ m$. Calculate the power of the pump in $kW$. Assume its efficiency is $50\%$.

$A$ wind-powered generator converts wind energy into electrical energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. For wind speed $v$,the electrical power output will be most likely proportional to

$A$ man does a given amount of work in $10 \ s$. Another man does the same amount of work in $20 \ s$. The ratio of the output power of the first man to the second man is:

$A$ body starts from rest, under the action of an engine working at a constant power and moves along a straight line. The displacement $s$ is given as a function of time $t$ as: