Question

he upper leg muscle (quadriceps) exerts a force of FQ = 1100 N, which is carried by a tendon over the kneecap (the patella) at the angles shown in the figure below. Find the magnitude in newtons and direction in degrees counter-clockwise from an axis directed to the left of the force exerted by the kneecap on the upper leg bone (the femur). magnitude N direction ° counter-clockwise from an axis directed to the left

Answer 1

along horizontal

Fxnet = Fx = FQ*cos55 + FQ*cos75 = 1100*cos55 + 1100*cos75 = 915.63 N

along vertical

Fynet = FQ*sin55 - FQ*sin75

Fy = 1100*sin55 - 1100*sin75

Fy = -161.45 N

magnitude = sqrt(Fx^2+Fy^2)

F = sqrt(915.63^2+161.45^2) = 929.7 = 930 N <<<<<----------ANSWER

direction = tan^-1(Fy/Fx) = 10 degrees <<<<<----------ANSWER