Solved University Question Papers May-2018

Solved University Question Papers

May-2018

Engineering Mechanics

Semester II (Mechanical/Civil) Regulation 2017

Time: Three Hours]

AU Solved Paper (40044)

[Maximum Marks: 100]

Answer ALL Questions

PART A - (10 x 220 Marks)

Q.1

Determine the resultant of the three concurrent F1 = 2i+ 3j - 2.5 k, F2 = -I + 5j - 3k and F3 = 7i-7j+6k. The forces are in Newton. 

[Refer example 2.12.14] 

Q.2

State the parallelgram law of foces. 

[Refer Two Marks Q.6 of chapter - 2] 

Q.3

Mention the required equilibrium conditions of a body applied with a system of non-concurrent, coplanar forces. 

[Refer Two Marks Q.3 of chapter - 4]

Q.4

A force F = 6Ni - 4j - 5N k is acting at a point P whose position vector from the origin O of the co-ordinate axes is 8 mm j − 4 mm k. Find the moment of this force about the origin. 

[Refer Two Marks Q.18 of chapter - 3]

Q.5

What is moment of inertia of traingular lamina (b×h) about its horizontal centroidal axis ? 

[Refer Two Marks Q.7 of chapter 6]

Q.6

State the parallel axis theorem. 

[Refer Two Marks Q.3 of chapter - 6] 

Q.7

Define coefficient of restitution. 

[Refer Two Marks Q.16 of chapter - 9] 

Q.8

State the work and energy principle. 

[Refer Two Marks Q.10 of chapter - 9]

Q.9

What is the force F required to just initiate the block shown in Fig. 1 to slide if the coefficient of friction between the surfaces in contact is 0.4 ?

[Refer Two Marks Q.6 of chapter - 2]

Q.10

A fan rotating at 50 rpm is being switched off and it will come to rest in 20 s. How many revolutions it has made before it comes to rest ? 

[Refer Two Marks Q.11 of chapter –11]

PART B - (5 × 13 = 65 Marks)

Q.11 

a) A transmission tower is held by three guy wires attached to a pin at A and anchored by bolts at B, C and D. If the tension in wire AB is 3.6 kN, determine the vertical force P exerted by the tower on the pin at A. 

[Refer similar example 2.12.22]

OR

b) Knowing that the tension is 1020 N in cable AB and 850 N in cable AC, determine, the magnitude and direction of the resultant of the forces exerted at A by the two cables. 

[Refer similar example 2.12.33]

Q.12 

a) It is known that a vertical force of 800 N is required to remove the nail at C from the board. As the nail first start moving, determine (a) that moment about B of the force exerted on the nail, (b) the magnitude of the force P which creates the same moment about B if α = 10 °, (c) the smallest force P which creates the same moment about B.

OR

b) Knowing that P = 210 N, replace the three couples with a single equivalent couple, specifying its magnitude and the direction of its axis.

Q.13 

a) Determine the center of gravity of unsymmetrical I section shown in Fig. 6. 

(Refer example 5.3.4)

OR

b) Find the moments of inertia about the centroidal axes for the section shown in Fig. 7. 

[Refer example 6.6.21]

Q.14 

a) Two vehicles approach each other in opposite lanes of straight horizontal roadway as shown in Figure. At time t = 0, the vechicles have the speeds and positions shown in the Fig. 8. Find the time and positions at which the vehicles meet if both continue to move with constant speed. 

[Refer example 9.1.41]

 OR

b) A steel ball of weight 60 N dropped onto a spring of stiffness 500 N/m from a height of 100 mm. Find the maximum deflection of the spring (use the work energy principle). 

[Refer similar example 9.3.11]

Q.15 

a) Determine the smallest force P required to move the block B if (a) Block A is restrained by cable CD as shown in Fig. 9. (b) Cable CD removed. Take the coefficients of frictions as μs = 0.30, μk = 0.25 between all surfaces of contact.

[Refer example 8.6.8]

OR

b) Determine the smallest force P required to lift the 13.34 kN load shown in Fig. 10. The coefficient of static firction between A and C and B and D is 0.3 and that between A and B is 0.4. 

[Refer example 8.10.2]

Q.16 

a) A camera of mass 240 g is mounted on a small tripod of mass 200 g. Assuming that the mass of the camera is uniformly distributed and that the line of action of the weight of the tripod passes through D, determine

a) the vertical components of the reactions at A, B and C when θ = 0 

b) the maximum value of 0 if the tripod is not to tip over.

 OR

b) A roller or radius r = 304.8 mm and weight = 2225 N is to be pulled over a curb of weight h = 152.4 nn by a horizontal force P applied to the end of a string wound round the circumference of the roller (Fig. 12) Find the magnitude of P. required to start the roller over the curb. 

[Refer similar example 2.11.23]