1st PROBLEM SETES 61

Instructions, PLEASE READ CAREFULLY:

1. The questions are available at 12PM, December 7, 2010, if you didn’t get it at this time, it’s not my responsibility.

2. Due date and time: Dec 10, 2010 @ 4 P.M. Submit in person. Appropriate penalties will be given for problem sets submitted after due date and time.

3. Answer the questions on separate sheets: no two questions will be found on the same sheet. Please use short bond paper. Do not write on the reverse side. (Scratch paper may be used, provided one side is clean.)

4. Answers should be in your own handwriting. No word processed answer.

PROBLEM SET PROPER: Show necessary solutions to the problems. Maintain 2-decimal places on partial and final answers. Use unit vector approach.

1. The 40-kg flowerpot is suspended from three wires and supported by the hooks at B and C (Fig. 1). Determine the tension in AB and AC for equilibrium.

2. The pipe of mass M, 30 kg, is supported at A by a system of five cords. Determine the force in each cord for equilibrium, θ = 60o. (Fig.2)

3. Blocks D and F weigh 5 lb each, block E weighs 8 lb and a = 4 ft. Determine the sag s for equilibrium as shown (Fig. 3). Neglect the size of the pulleys.

4. The shaft S exerts three force components on the die D (Fig. 4). Find the magnitude and direction of the resultant force. Force F2 acts within the octant shown.

5. Three cables are attached to a bracket as shown (Fig. 5). Determine the force directed from B to E, force applied at point D, force applied at point C, and the magnitude and direction of the resultant force.

6. The climber A is being helped up an icy slope by two friends. His mass is 80 kg, and the direction cosines of the force exerted on him by the slope are cos = -0.286, cos = 0.429, and cos = 0.857. The y axis is vertical. If the climber is in equilibrium in the position shown (Fig.6), calculate the magnitude and direction of the resultant force.

FIG. 1FIG. 2

FIG. 3

FIG. 4

C

A B

D

100 mm

Z

100 mm

50 mm

50 mm

FIG. 5

FIG. 6