ch06-p021 - 21. If the block is sliding then we compute the...

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

View Full Document Right Arrow Icon
21. If the block is sliding then we compute the kinetic friction from Eq. 6-2; if it is not sliding, then we determine the extent of static friction from applying Newton’s law, with zero acceleration, to the x axis (which is parallel to the incline surface). The question of whether or not it is sliding is therefore crucial, and depends on the maximum static friction force, as calculated from Eq. 6-1. The forces are resolved in the incline plane coordinate system in Figure 6-5 in the textbook. The acceleration, if there is any, is along the x axis, and we are taking uphill as + x . The net force along the y axis, then, is certainly zero, which provides the following relationship: 0c o s yN FF W θ = ¡ = ¦ G where W = mg = 45 N is the weight of the block, and = 15° is the incline angle. Thus, F N = 43.5 N, which implies that the maximum static friction force should be f s ,max = (0.50) (43.5 N) = 21.7 N. (a) For ˆ ( 5.0 N)i P =− G , Newton’s second law, applied to the
Background image of page 1
This is the end of the preview. Sign up to access the rest of the 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