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