3/5/10
Post date: Mar 05, 2010 9:10:13 PM
Bell Ringer: What is the coefficient of static friction between your shoe and wood?
Help with homework problems
Shoe on ramp problem
Place your shoe on a wooden ramp
Lift the ramp to a larger and larger angle until your shoe just barely begins to slide
Measure the angle of the ramp at this point
Lift your shoe using a spring scale to find the weight of the shoe
Using the Fnet = ma equation (in the perpendicular direction and in the parallel direction), calculate the normal force and force of friction
Use Fn and Ff to calculate the coefficient of friction
Vector practice problems (due Monday)
Page 130: 23, 27, 29, 34-36 (only 34-36 are problems involving inclined planes)
Answers to problems:
23. a) 2.2 m/s/s
b) 340 N up
27. 279 N up
29. 74 N, 253 degrees
34. 123 N
35. a) 111N
b) 140 N, up
c) 100N, down
d) 0.327
36. 11 N, up the plane