# Homework Help: Hydraulic Brake Problem How to Start?

1. Nov 18, 2011

### DrunkApple

1. The problem statement, all variables and given/known data
A hydraulic brake system is shown. The
area of the piston in the master cylinder is
6.41 cm2, and the area of the piston in the
brake cylinder is 1.69 cm2. The coefficient of
kinetic friction between the brake shoe and
the wheel drum is 0.449.
How large is the frictional force between the
brake shoe and the wheel drum when a force
of 44 N is exerted on the pedal?

2. Relevant equations
$\frac{F1}{A1}$ = $\frac{F2}{A2}\frac{}{}$
A1 = 6.41 cm$^{2}$
A2 = 1.69 cm$^{2}$
F = 44 N
μ = 0.449
F = μF$_{n}$

3. The attempt at a solution
I don't know how to relate coefficient to this problem. Would you give me some hint please?

2. Nov 19, 2011

### Simon Bridge

It is difficult to see what your problem is... you can convert the force applied to the pedal to force applied to the drum?