A car of mass m starts from rest and accelerates so that instantaneous power delivered to the car has a constant magnitude P. The instantaneous velocity of the car is proportional to??
Ans t 1/2
how to solve??

Hint: recall that power is defined as change in energy per unit time. Take a stab at this, and post back with what you come up with.

Hint: recall that power is defined as change in energy per unit time. Take a stab at this, and post back with what you come up with.

1/2 mv 2= Pxt.. thus v is proportional to under root of t.. Right?

Yes - that's it.