# Homework Help: A brick is sliding down a ramp

1. Jan 5, 2009

### dreamgirl

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

A brick is sliding down a ramp

Anet / acceleration = .5 m/s^2
m= 2 kg
M = the coefficient of friction = unknown or ?

3. The attempt at a solution

I'm just stuck on the last part

well first this is my work so far:

90-delta=
90 - 35 = 55

Fg= (2)(-9.8)
Fg= -19.6

Fg x = Fg cos (-) or -19.6 cos 55 = -11.2
Fg y = Fg sin (-) or -19.6 sin 55 = -16.1

Fn= 16.1
---------------

This is where i get stuck.
I don't know how to find M from here

Last edited: Jan 5, 2009
2. Jan 5, 2009

### jgens

What quantity is M supposed to designate?

3. Jan 5, 2009

### dreamgirl

M = the coefficient of friction
idk if that helps? :(

4. Jan 5, 2009

### jgens

Well, since the coefficient of friction is defined as M = (Ff/Fn), all you need is to calculate the friction force.

5. Jan 5, 2009

### dreamgirl

last question how do i calculate the friction force? :[

6. Jan 5, 2009

### jgens

Well you know the acceleration of the block and its mass, so first you need to apply Newton's second law to find the net force acting on the block. Then using what you know about the net force calculate the friction force. Fnet = Fgx - Ff.

7. Jan 6, 2009

### dreamgirl

okay i think i got it now

THANK YOU SO MUCH<3333333333