How Fast Must an Inclined Plane Accelerate for a Block to Slide Down?

[jromega3]

Homework Statement

An inclined plane that makes an angle of 28° to the horizontal is mounted on wheels. A small block of mass m = 2 kg rests on the plane, held there by a coefficient of static friction µ = 0.66.

The plane is accelerating to the right, as shown. What is the minimum acceleration in order that the block slides down the plane?

Brief picture...
https://tycho-s.phys.washington.edu/cgi/courses/shell/common/showme.pl?courses/phys121/autumn08/homework/06b/accelerated_incline_NWT/7.gif

Homework Equations

The Attempt at a Solution

So I've made a FBD...and pretty much stuck from there. My axis is regular, in the direction of the acceleration.
F (x direction)=mgsin28 -sin62uFN...where U is the coefficient of static friction
F (y direction=-mg + mgcos28 + cos62uFN.

I believe these are right, and not sure where to go from here.
I solved for FN and got around 7.4N...not sure how to relate this to the acceleration needed for the block to slide down. As usual, thanks for all help

 

[tiny-tim]

Hi jromega3!

It's simplest to calculate components along the slope …

what is the friction force needed to keep the block still …

at what acceleration does that force equal µN?