Quick Question Regarding Smooth Inclined Plan

[FaraDazed]

Homework Statement

an block of mass 6kg is sliding down an inclined plane inclined at 45° to the horizontal. Find the acceleration of the mass.

Homework Equations

F=ma

The Attempt at a Solution

Is it correct that the weight times sin45 will equal ma, because that's how i first did it but now I am going through the problem again before handing it in and drew the sketch again and I was thinking what about the weight times cos45? wouldn't that AND wsin45 cause acceleration?

 

[Doc Al]

Only the component of the weight parallel to the incline (mg sinθ) acts to accelerate the block. Perpendicular to the incline, the normal force acts to cancel the component of the weight (mg cosθ).

 

[FaraDazed]

Only the component of the weight parallel to the incline (mg sinθ) acts to accelerate the block. Perpendicular to the incline, the normal force acts to cancel the component of the weight (mg cosθ).

Thanks :)