Fictional force problem given a slope(grade)?

fictional force problem....given a slope(grade)???

A 1000kg car is moving down a road with a slope(grade) of 15% at a constant speed of 15m/s. What is the direction and magnitude of the frictional force?

So...

V= 15m/s
a= 0 (constant)

The slope really throws me off..I don't know where to start! And the percent.... What am I supposed to do with that??

 

Re: fictional force problem....given a slope(grade)???

Zero? The frictional force would be zero. So, then the grade (the incline) was given just to make us think and try to picture it, I guess.

Ok, how about if we're given the grade and told that the the car was speeding up at 3m/s^2

I know the mass (1000kg) and I think theta would be the percentage of 15? Would the velocity be the force N or friction f? and where would I plug in my acceleration?

I think f=ma ; Ncos(theta) + fcos(theta)-mg

I hope I'm on the right track...the prof. has only touched on the subject and he hasnt assigned a textbook..so really I'm trying to google what I can but its more complicated than I can do on my own. Any help would be appreciated :)

 

Re: fictional force problem....given a slope(grade)???

Would it be equal to the mass?