# Power required to move up an incline

1. Mar 17, 2009

### Ut Prosim

1. The problem statement, all variables and given/known data

What power is needed to drive a car at 60 km/h up a 10% grade.

mass=1800kg
v=60km/h
theta=5.7106
g= 9.81 m/s^2

2. Relevant equations

P = Fv
P_ave= W/T
w=mg
F=ma

3. The attempt at a solution

I drew my diagram and FBD.

Since Fy=mAy=0..

0=N-sin(5.7106)
N=1755.2477

I know that Ax will be 0 since the velocity is constant, and I need to find the frictional constant:

mAx=0=F-uk-mgcos(5.7106)

But I don't have F, since it's what I'm trying to find..and this is where I've been stuck.

2. Mar 17, 2009

### LowlyPion

Welcome to PF.

Maybe consider the rate of change of potential energy?

3. Mar 17, 2009

### Ut Prosim

Problem with that is we haven't learned anything about energy yet so we are supposed to use regular Work, Power, and other Motion formulas.

4. Mar 17, 2009

### LowlyPion

OK. So consider then the force of gravity along the incline.

The car travels at 16.667 m/s, so in 1 second, what force was required to overcome gravity over that distance?

That gives you W per sec = F*d per sec.