(7%) Problem 6: The frictional forces in joints are relatively small in all circumstances except when the joints deteriorate, such as from injury or arthritis. Increased frictional forces can cause further damage and pain. The knee joint is where the femur (a bone located in the thigh) meets the tibia (a bone located in the lower leg). Assume that half of the the weight, F w, of a person is supported by each leg resulting in normal forces between the femur and tibia. Suppose that F W =896 N, and the coefcients of static and kinetic friction are s =0.0165 and #k = 0.0131, respectively. Tran .Theresa , ttran55@rnail.sfsu.edu 33% Part (b) Suppose the person steps onto a horizontal conveyor belt. What is the maximum value of the static frictional force in one knee joint? f max N Grade Summary Deductions 0% Potential 100% sin() cos() tan() 7 8 C HOME cotan() asin() acos() E A Submissions 4 5 6 Attempts remaining: 6 atan() acotan() sinh() 1 2 3 (1% per attempt) cosh() tanh() cotanh() + 0 END detailed view Degrees Radians VO BACKSPA DECLEAR Submit Hint Feedback I give up! Hints: 1 for a 0% deduction. Hints remaining: 0 Feedback: 1% deduction per feedback. -The force of static friction varies between zero and a maximum value given by fmax= usFN, where us is the coefficient of static friction, and FN is the magnitude of the normal forces tibia and the femur exert on each other. Recall that the weight is distributed equally between the legs. 4 33% Part (c) The person jumps from a short wall to the ground below, landing evenly on both feet. The effects of impact with the ground are equivalent to increasing the person's weight to 19.6 times the actual weight. What is the maximum value of the static frictional force in one knee joint as the person's feet make impact with the ground