Question

If the engine of a car of mass m is capable of power P, the minimum time needed for the car to accelerate from rest to a speed v is?

Answer 1

Gives

Power =P

Speed=v

Only kinetic energy existing potential energy zero

∆E=K.E+P.E

P.E=0

∆E=K

$∆E=\frac{1}{2}mv^2$

Power

$P=\frac{∆E}{t}$

∆E=Pt

$\frac{1}{2}mv^2=Pt$

$t=\frac{mv^2}{2P}$