# Homework Help: Normal Force and Static Frictional Force

1. Jan 29, 2008

### confounded

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

A car (m = 1710 kg) is parked on a road that rises 14.7 ° above the horizontal. What are the magnitudes of (a) the normal force and (b) the static frictional force that the ground exerts on the tires?

Coefficient of static friction: rubber on dry concrete: 1.0

2. Relevant equations

F=ma
Fs max = coefficient of friction x normal force

3. The attempt at a solution

I drew some pictures, but I'm slightly computer illiterate so..sorry. Anyway, not really sure, but here's what I got:

F= (1710 kg)(9.8 m/s^2)
F= 16758 N

Attempt at solution of the normal force:

16758 N x sin (14.7) = 4252.48 N

Static Frictional Force:

(I'm really not sure of this, but I'll go ahead)

(4252.48 N)(1.0)= 4252.48

I'm just at my wit's end. I've been trying to figure out this problem for two hours straight. I have to enter my answers in online, and I can only have three significant digits, yet I can't enter in scientific notation, so...I just don't know! Help please!

2. Jan 29, 2008

### foxjwill

You're thinking too hard about it. If you figure out the sum of forces you have

\begin{align*} \sum F_x &= f_s - mg\sin\theta = 0\\ \sum F_y &= F_N - mg\cos\theta = 0 \end{align*}​