Question

What is power? show that power= force * velocity? calculate the power of a body os mass 10 kg accelerating with 10m/s2 acquires a velocity of 5m/s

Answer 1

Power is defined as the rate of the doing work.

As we know ,
Work done = Force × Displacement
W = F.s
As P = rate of doing work

$$\begin{gathered} P=\frac{d\left(F.s\right)}{dt} \\ =F\frac{ds}{dt} \\ =F.v \\ wherevisthevelocity=\frac{ds}{dt} \end{gathered}$$

mass=10kg
g=10ms^-2

v=5m/s
3rd eqn of motion =
v²=u²+2gh
5*5=0+2*10*h
=25=20h
5/4=h
1.25=h

so 1st eqn =
v=u+at
5=0+10t
0.5=t

power= workdone/time
=mgh/t
=10*10*1.25/0.5
=125/0.5
=250watt is the power......