UNIT 5 EXERCISES

1) A skier has just begun descending a 30o slope. Assuming the coefficient of kinetic friction is 0.10,

a) draw a force diagram

b) find her acceleration

c) suppose, instead the snow is slushy and she moves down the hill at a constant speed. What will the coefficient of kinetic friction be? Show your work.

2) Determine the net compressive force acting on the patella as a result of the action of the quadriceps muscle (Fm upward) and the patellar tendon (Ft downward) as shown in the diagram below. Take the angle between the muscle group and the tendon to be 160o, and assume the leg is bent symmetrically so that Fm = Ft = 100N. Show your work.

(From Physics: Algebra/Trig Second Edition, Brooks/Cole Publishing Company, 1998.)

3) The diagram below shows two masses free to move, M = 50kg and m = 20kg, connected by a massless cable on two frictionless pulleys.

a) Draw a force diagram for each mass.

b) Are the masses accelerating? Compare the acceleration of mass M and mass m. Explain.

c) Find the tensile force in the cable. Show your work.

d) Find the acceleration of each mass. Show your work.