# Mechanics: Force-Angle Problem

1. Jan 27, 2013

### morrisj753

1. The problem statement, all variables and given/known data
A uniform rectangular wood block of mass M, with length b and height a, rests on an incline as shown. The incline and the wood block have a coeﬃcient of static friction, µs. The incline is moved upwards from an angle of zero through an angle θ. At some critical angle the block will either tip over or slip down the plane. Determine the relationship between a, b, and µs such that the block will tip over (and not slip) at the critical angle. The box is rectangular, and a =6 b.

2. Relevant equations
Ff = μ x Fn
F = ma

3. The attempt at a solution
What are the conditions in which the box may tip over? I get what the question is asking of me but I don't really understand how I should first approach it.

2. Jan 27, 2013

### cepheid

Staff Emeritus
3. Jan 27, 2013

### tiny-tim

hi morrisj753!
the box will tip if the vertical line through its centre of mass does not go through its area of contact with the surface