ENGINEERING MECHANICS Assignment-1(Last Date of submission: 21-01-2014) 1. Two control rods are attached at A to lever AB as shown in fig.1. Using trigonometry and knowing that the force in the left-hand rod is F1 = 30 N, determine (a) the required force F2 in the right-hand rod if the resultant R of the forces exerted by the rods on the lever is to be vertical, (b) the corresponding magnitude of R. 2. Four forces act on bolt A as shown in fig.2. Determine the resultant of the forces on the bolt. 3. Determine the resultant of the three forces shown in fig.3. 4. Boom AB is held in the position shown by three cables as shown in fig.4. Knowing that the tensions in cables AC and AD are 900N and 1200 N, respectively, determine (a) the tension in cable AE if the resultant of the tensions exerted at point A of the boom must be directed along AB, (b) the corresponding magnitude of the resultant. 5. Two cables are tied together at C and are loaded as shown in fig.5. Determine the tension (a) in cable AC, (b) in cable BC. 6. Two traffic signals are temporarily suspended from a cable as shown in fig.6. Knowing that the signal at B weighs 300 N, determine the weight of the signal at C. 7. The force P is applied to a small wheel that rolls on the cable ACB as shown in fig.7. Knowing that the tension in both parts of the cable is 140 N, determine the magnitude and direction of P. 8. A system of four forces acting on a body is shown in fig. 8. Determine the resultant force and its direction. 9. A mass of 45 kg is suspended by a rope from a ceiling as shown in fig.9. The mass is pulled by a horizontal force until the rope makes an angle of 70˚ with the ceiling. Find the horizontal force and the tension in the rope. 10. The Bar AC, 10m long supports a load of 6000N as shown in fig.10. The cable BC is horizontal and 5m long. Determine the forces in the cable and the bar. 11. Determine the tension in the cables AB, and AC required to hold the 40KG crate shown in fig 11. Find the tension in the cable AC and BC. 12. A horizontal line PQRS is 12m long where PQ=QR=RS=4m.Forces of 1000,1500, 500 N act at P,Q,R and S respectively and action of these forces make angles of 90˚, 60˚, 45˚ and 30˚ respectively