Inclined Plane-Acceleration of Object

[darkmasterz8]

Homework Statement

[PLAIN]http://img375.imageshack.us/img375/7161/physics.png [Broken]
I have to find the acceleration of A to B.

Homework Equations

My problem is that I'm not sure to add normal force with the force of gravity x component.
Fnetx=Fgx
m*Ax=m*g*sin(theta)
Ax=g*sin(theta)

The Attempt at a Solution

Ax=9.8*sin(20)
=3.35 m/s^2

Should I have added normal force to the Fgx since Fnet is the sum of all forces? I thought you would only include this if friction was given.

 

[CheckMate]

Normal force is "canceled out" with the component of gravity perpendicular to the ramp (mgcos(theta)). That is why the object doesn't go through the plank and doesn't get propelled out of it either.

Correct, normal force would be included with friction.

The problem with your solution is that you haven't defined what the direction of x-axis is.
It could be up down, left, right, down the ramp, up the ramp...

Are you sure that's what the question is ? It's better to take a look at the question taken from the textbook.