1. Determine the force F needed to hold the 4-kg lamp in the position shown.
2. The patella P located in the human knee joint is subjected to tendon forces T1 and T2 and a force F exerted on the patella by the femoral articular A. If the directions of these forces are estimated from an X-ray as shown, determine the magnitudes of T1 and F when the tendon force T2 = 6 lb.. The forces are concurrent at point O.
3. A continuous of total length 4 m is wrapped around the small frictionless pulleys at A, B, C, and D. If the stiffness of each spring is k = 500 N/m and each spring is stretched 300 mm, determine the mass m of each block. Neglect the weight of the pulleys and cords. The springs are unstretched when d = 2 m.
4. Determine the force in each strut and tell whether it is in tension or compression.
5. The ends of the three cables are attached to ring at A and to the edge of a uniform 150-kg plate. Determine the tension in each of the cables for equilibrium.
6. The joint O of a space frame is subjected to four forces. Strut OA lies in the x-y plane and strut OB lies in the y-z plane. Determine the force acting in each if the three struts required for equilibrium of the joint. Set = 45°.
7. A "scale" is constructed with a 4-ft-long cord and the 10-lb block D. The cord is fixed to a pin at A and passes over two small pulleys at B and C. Determine the weight of the suspended block E if the system is in equilibrium when s = 1.5 ft.
8. Determine the magnitudes ofthe forces P, R, and F required for equillibrium of point O.
9. Determine the magnitude and direction of the resultant force FAB exerted along link AB by the tractive apparatus shown. The suspended mass is 10 kg. Neglect the size of the pulley at A.
10. Determine the tension developed in cables OD and OB and the strut OC, required to support the 500-lb crate. The spring OA has an unstretched length of 0.2 ft and a stiffness of kOA = 350lb/ft. The force in the strut acts along the axis of the strut.