Box sliding on 35 degree grade

[joel amos]

A box slides down a frictionless plane that makes an angle of 35 degrees with the horizontal. A horizontal force of half the box's weight presses the box against the plane. What is the box's acceleration?

I'm confused as to what kind of effect would a horizontal force have on an object sliding on a grade? I'm not really sure how to do this problem. Any help is appreciated. Thanks!

 

[howie8594]

I don't understand what this problem is saying, because any object you put on a frictionless 35 degree incline will always accelerate at the same rate regardless of mass. Is the horizontal force you're talking about an extra force being applied to the block by something else?

 

[joel amos]

The posed question is the question in its entirety...and off of a test at that.

 

[lewando]

Start by drawing (and posting) the free body diagram.

 

[joel amos]

Here 'tis. I wasn't exactly sure what the horizontal force was...
http://imageshack.us/a/img854/8639/problem4l.png

 

[lewando]

The horizontal force should be applied horizontally. There will be a normal reaction force in response to this horizontal force.

mg is a force and there will be a normal reaction force to this as well.

Total of 4 forces. Your F_F looks wrong. As well as your mg cosθ and mg sinθ.