Question

A particle of mass m is driven by a machine that delivers a constant power of K watts. If the particle starts from rest the force on then particle at time t is :

• A.
• B.
• C.
• D.

Answer 1

The correct option is C.

The power (P) is given by,

$P=Fv$

where F = Force acting on the body and v = velocity of the body

Since the particle starts from rest initial velocity = u = 0 and

Final velocity = $v=u+at=0+\left(F/m\right)t=\left(F/m\right)t$

$K=Fv=F\left(\frac{F}{m}\right)t$

$K=\frac{F^2}{m}t$

$\therefore F=\sqrt{\frac{mK}{t}}$