How Do You Calculate the Acceleration of a 42kg Ice Block Sliding Down a Slope?

[dhymas]

Urgent! Acceleration of an ice block given mass

Homework Statement

A 42 kg block of ice slides down a slope of 30 degrees. Assuming friction is negligible, what is the acceleration of the block down the incline?

Homework Equations

Fnet=ma_x
W=mg

The Attempt at a Solution

I have drawn a free body diagram correctly. I have the block on a slope of 30 degrees. I have weight acting downward and Normal Force acting perpendicular to the slope. I just want to make sure that I am doing this right.

Fnet=ma_x
I know I have mass already and I can get weight by multiplying 42 by 9.8 m/s²
My problem is what numbers would I use for Fnet? Just the X component for weight or also the Y component?

 

[PhanthomJay]

What you want to be sure to do is label the x-axis as the axis parallel to the incline, and the y-axis as the axis perpendicular to the incline. In this manner, there will be no acceleration along the y-axis because the block does not move in that 'y' direction (it doesn't jump off the plane because the weight component in the 'y' direction is balanced by the normal force in the 'y' direction). So what is the net force acting in the 'x' direction and what is its magnitude?