Thread: Mechanics problem!

Hello! i have an applied mechanics proble. dont know how to start off.. or do any other bit for that matter. can somebody share some help? =)


The figure represents the slow flexion and extension movements of the leg and thigh. the length of the leg is L=0,4m, and the weight of the leg is m=4.8Kg, and the thigh m=9,8Kg. We´re also given the distances to the center of mass of the thigh (B) and leg (D) from the extremities. ( AB= CD= 0.43L ).
Determine the force F in function to angle alfa, and the strength of the joint connections of the hip(A), the knee(C) and the ankle(E).

Each of the leg segments is pulled by gravity downwards. Because of the angle of the legs, there is a net force in the direction opposite to F.

The weights let you figure out mg, the dimensions let you figure out the angles.

I don't know what is meant by "strength of joint connection".

"strength of joint connection" i suppose is equivalent the force apllied at each
point...? yep, but how do i calculate the net force?

Hi

Resolve the forces verticly and horizontally then take moments about one of the points (or two for the points) and the equations will drop out.