Question

. A person laying in a supine position as shown in the figure below executes a leg lift by flexing his hip while keeping the lower leg straight. The initial angular acceleration of the thigh is 3 rad/s. Use the paall adis theorem to find the momehts of inertia about the hip and then the equations of motion to determine the joint reaction torques in the hip and Thigh: I 45 cm,dr - 18 cm, mr 8 kg, IGT 4000 kg'cm2 (about the COM of the thigh) Lower leg: du 18 cm, mu 5 kg, a.500 kg'cm2 (about the COM of the lower leg)

Answer 1

Given that :

I'_LL = m_LL (I_T + d_LL)² = 5 (45 + 18)² = 19845 kgcm²

Total moment of inertia is given as

I = I'_LL + I_GT + I_GL

I = 19845 + 4000 + 500

I = 24345 kgcm²

Torque on hip is given as

I_h = I $\alpha$ = (24345) (3) = 73035