Power needed to maintain a car's speed

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zuq

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Hi guys

I am building an electric go kart and need some advice on its mechanical design.
Just check my maths please,

if I have a 85kg kart + 85 kg driver (170kg), and I want to accelerate to 6.94m/s in 2seconds this is the power I need...
Kinetic energy= 0.5*170kg*(6.94m/s)^2= 4kJ
Then the power is 4kJ/2sec = 2KW (mechanical)

Now how much power do I need to maintain this speed???
Will it just be the power required to overcome the rolling resistance, drag and grade???
say combination of all the these is 5% of weight..
.05*170kg=8.5kg . in Newtons = 8.5kg*9.8N/kg =83.3N
P=Force * Velocity = 83.3 * 6.94=578 W (mechanical)

So is my method of calculating power required to maintain speed and get up to this speed correct ???
 

will the drag on the cart total can be 5% of weight?
while friction and grade seems logical , i had this point.
 

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