Homework Help: Physics

Posted by Ashley on Friday, September 25, 2009 at 10:46am.

A small box is held in place against a rough vertical wall by someone pushing on it with a force directed upward at 28degrees above the horizontal. The coefficients of static and kinetic friction between the box and wall are 0.40 and 0.30, respectively. The box slides down unless the applied force has magnitude 18 N.

What is the mass of the box in kilograms?

Physics - BeeGray, Saturday, February 12, 2011 at 4:01pm
1. Find Fn
Fn=18N*cos(28)=15.9N

2. Find Forces in Y direction to solve for m
18N*sin(28)+Fn*fs
18N*sin(28)+(15.9N*0.4)-9.8m=0

Ans: m=1.5kg
Physics - ale, Wednesday, October 12, 2011 at 7:13pm
where did you get the 0.4??

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