# Mechanics problem!

• Jan 19th 2010, 07:15 AM
Corum
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).
• Jan 19th 2010, 06:15 PM
qmech
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".
• Jan 19th 2010, 11:49 PM
Corum
"strength of joint connection" i suppose is equivalent the force apllied at each
point...? yep, but how do i calculate the net force?
• Jan 20th 2010, 03:05 AM
Bwts
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.