Engineering Mechanics 1. Determine the forces in the members BE and BD of the truss which supports the load

as shown in fig. All interior angles are 600 and 1200.

( force acting at G is 100N )

2. Determine the force in each member of the truss as shown in fig. and tabulate the

results with nature of force in the members.

3. Determine the force in members FE, FC and BC OF the truss using method of sections

and state if the members are in tension or compression.

Solution: FBD:

4. Cable ABCD supports the 4kN and 6kN loads at B and C as shown in the fig.

Determine the maximum tension0 in cable and sag of point B.

5. The cable segment supported at A and B. Determine the supports reaction and

maximum tension in segment of cable.

Solution:

6. Determine the components of reactions at supports A and B for the frame loaded and

supported as shown in fig.

7. A force P=mg/6 is required to lower the cylinder with the cord making 1.25 turns

around the fixed shaft. Determine the coefficient of friction µs between the cord and

shaft.

Solution:

8. The uniform pole of length l and mass m is leaned against the vertical wall as shown in

fig. if µs = 0.25(between pole and supporting surfaces).Calculate the maximum angle θ

at which the pole may place before it starts slip.

cos θ = 1.875 sin θ

θ = 28.070

9. A block of mass m rest on a frictional plane which makes an angle α with the

horizontal as shown in the fig. If the coefficient of friction between the block and the

frictional plane is 0.2, determine the angle α for limiting condition.

Solution: for limiting condition,

tan α = tan φ = 0.2

α= 11.310

10. The 30kg pipe is supported at A by a system of five cords as shown in fig. Determine

the force in each cord for equilibrium.

Solution:

11. Three cables are joined at the junction C as shown in the fig. Determine the tension in

cable AC and BC caused by the weight of the 30kg cylinder.

12. The 20kg homogeneous smooth sphere rests on the two inclines as shown in fig.

Determine the contact forces at A and B.

13. Determine the reactions at roller A and pin B for equilibrium of member ACB as

shown in fig.

14. A beam supports a load varying uniformly from an intensity of w1 kN/m at left end to

w2 kN/m at right end as shown in fig. If the reactions RA=6kN and RB=12kN,

determine the intensity of loading w1 and w2.

15. A simply supported beam AB of span 6m is loaded and supported as shown in fig.

Find the reactions at support A and B.

Solution:

16. The square steel plate has a mass of 1800 kg with mass center G as

shown in fig. Determine the tension in each cable so that the plate

remains horizontal.

17. Determine the magnitude and direction of a resultant force of a given

force system as shown in fig. and locate its point of application on the

slab.

18. Two spheres A and B diameter 80 mm and 120 mm respectively are held

in equilibrium by separate strings as shown in fig. Sphere B rests against

vertical wall. If masses of spheres A and B are 10 kg and 20 kg.

Determine the tension in the string and reactions at point of contact.

Solution:

F.B.D.

19. Determine the component of reaction at hinge A and tension in the cable

BC as shown in fig.

20. Four parallel bolting forces act on the rim of the circular cover plate as shown in fig.

If the resultant force 750 N is passing through (0.15 m,- 0.10 m) from the origin O,

determine the magnitude of forces P1 and P2.

Solution: Given force system is in x-y plane.

All forces acting parallel to z-axis and resultant acting at (0.15, -0.10, 0)

Now, by Varignon’s theorm;

Taking the moment about x-axis; -100×0.75+P1 ×0.75 = 750×0.10

P1 = 200 N

Again, taking the moment about y-axis; P2 × 0.75 – 150 × 0.75 = 750 × 0.15

P2 = 300 N.