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# Help with deriving a physics equation?

I was given a question and from that we are supposed to derive an equation using only the variables in the question and gravity (g) if needed to get the following equation and I am stuck on this one, any help would be great, thanks, best answer!

An electric motor is attached to a car of mass m. The motor applies power P to the car for t seconds. What is the velocity (v) of the car?

Answer: v= square root of 2Pt/m

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- debydeteLv 79 years agoFavorite Answer
From Work-Energy Theorem the work done by the motor equals the car's change in Kinetic Energy.

Assuming the initial Kinetic Energy is zero (car starts from rest) this isv written;

W = (1/2)mv^2

By definition, Power is the rate of doing work;

P = W/t

Elliminate "W" from the eqs and solve for "v".

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