What Is the Average Power Output of a Race Car's Motor During Acceleration?

[k0k]

A 1250-kg race car accelerates uniformly from rest to 30.0m/s in 4.00s on a horizontal surface with no friction. What must be the average power output of its motor? (Ans:141kW)

--
P=E/t
F=ma
Ek=1/2mv^2

--

P=E/t
P=Ek/t
=(.5X1250kgX15.0m/s^2) / (4.00s)
=35156.25 W

How exactly do I start this off? I assume that the change in energy should be kinetic only, right?.

 

[OmCheeto]

A 1250-kg race car accelerates uniformly from rest to 30.0m/s in 4.00s on a horizontal surface with no friction. What must be the average power output of its motor? (Ans:141kW)

--
P=E/t
F=ma
Ek=1/2mv^2

--

P=E/t
P=Ek/t
=(.5X1250kgX15.0m/s^2) / (4.00s)
=35156.25 W

How exactly do I start this off? I assume that the change in energy should be kinetic only, right?.

I think you would have had the correct answer had you not replaced the given 30 m/s with 15 m/s.

 

[k0k]

OH, okay got it now. : D
Thanks