HW7_hints

HW7_hints - Homework 7 Hints Please first read the Sample Problems 3/2 and 3/3 on page P128-129 3/2 x axis should be selected along the slope It is

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Homework 7 Hints Please first read the Sample Problems 3/2 and 3/3 on page P128-129. 3/2. x axis should be selected along the slope. It is easy to calculate N in terms of mg and . Now, you have to judge whether you should use 15 θ = D s μ or k (the coefficient of kinetic friction). (a). Notice, movement is down and friction is up. Check the impending motion: Calculate the (friction) static force static F to keep the mass static on slope from . In the impending motion, mass will immediately start to move, but does not move yet. Therefore 0 x F = x a is equal to zero. Compare with 127 static FN = s N to see if movement occurs or not. In this case, movement does occur. x x Fm a = is used to calculate . a k is used to compute kinetic friction. m/sec 1.12 a = 2 down. (b). (c). Repeat above procedures. Notice: friction is up. (c). 2.04 a = m/sec 2 3/21.
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This note was uploaded on 09/27/2008 for the course ME 212 taught by Professor Staff during the Spring '05 term at Cal Poly.

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