ch06-p094

# ch06-p094 - 94(a The x component of F tries to move the...

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 94. (a) The x component of F tries to move the crate while its y component indirectly contributes to the inhibiting effects of friction (by increasing the normal force). Newton’s second law implies x direction: Fcosθ – fs = 0 y direction: FN – Fsinθ – mg = 0. To be “on the verge of sliding” means fs = fs,max = μsFN (Eq. 6-1). Solving these equations for F (actually, for the ratio of F to mg) yields → μs F = . mg cos θ − μ s sin θ This is plotted on the right (θ in degrees). (b) The denominator of our expression (for F/mg) vanishes when cos θ − μ s sin θ = 0 θinf = tan −1 1 μs 1 −1 For μ s = 0.70 , we obtain θ inf = tan μ = 55° . s (c) Reducing the coefficient means increasing the angle by the condition in part (b). 1 −1 (d) For μ s = 0.60 we have θ inf = tan μ = 59° . s ...
View Full Document

## This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.

Ask a homework question - tutors are online