Engineering Mechanics

http://passbtechexams.blogspot.com/ http://zakkam.blogspot.com/

[EURME-301]

B.TECH DEGREE EXAMINATION

Mechanical Engineering

III SEMESTER

(Supplementary)

ENGINEERING MECHANICS

(Effective from the admitted batch 2008–09)

Time: 3 Hours Max.Marks: 60

----------------------------------------------------------------------------------------------------

Instructions: Each Unit carries 12 marks.

Answer all units choosing one question from each unit.

All parts of the unit must be answered in one place only.

Figures in the right hand margin indicate marks allotted.

----------------------------------------------------------------------------------------------------

UNIT-I

1. a) A rigid bar AB is supported in a vertical plane and carries

a load Q at its free end as shown in fig . Neglecting

the weight of the bar it self , compute the magnitude of the

tensile force S induced in the horizontal String CD 8









b) State and prove lamiys theorem 4

OR

2. a) Two blocks of weight W and W rest on a rough inclined plane

1 2



and are connected by a short piece of string as shown in fig .

If the coefficient of friction are 10.2 and m2 =0.3 ,

respectively , find the angle of inclination of the plane for

which sliding will impend . Assume W =W 1 2









UNIT-II

3. a) Locate the centroid C of the shaded area OABD shown in fig 6









http://zakkam.blogspot.com/







b) The cross section of a culvert is shown in fig compute the



(All units are Cm)

OR

4. The warren truss loaded as shown in fig. is supported by binge

at G and by a roller at C. Use the method of sections to compute

the force in bars BC , DF and CE 12

b) The cross section of a culvert is shown in fig

compute the moment of inertia (all units are in cm)









http://zakkam.blogspot.com/

http://passbtechexams.blogspot.com/

OR

4. The warren truss loaded as shown in fig. is

supported by binge at G and by a roller at C. Use the

method of sections to compute the force in bars BC, DF

and CE 12

UNIT-III

5. a) A 4-bar linkage in formed with linkage AB ,

BC , CD and DA . Determine the linear velocity of the

binge B and the angular velocity of the link AB when

the link DC is rotating at 300RPM clock wise . Assume

link CD makes an angle 600 with horizontal . The

linkage AD is fixed their lengths are given below

AB=30CM, BC=40CM, CD=45CM, AD=75CM

6

b) Two ships A and B are 60 Km a part, A being

north of B. Ship A is steaming due south – east with a

velocity of 25Km/hr. and ship B is steaming along east

with a speed of 10 Km/hr. Two ships can exchange

signals when they are within 30Km from each other.

Determine when they can start signaling from the starting

and how long they will



OR

6. a) A ball is projected from a ground at an angle of

600 with the horizontal with a velocity of 30 m/sec.

Find the distance of the ball from the point of

projection after 2 sec and its height above the ground .

take g = 9.81 m / sec2

b) A shot is fired with a velocity of 30 m / sec from a

point15 m in front of a vertical wall 6 m high. Find the

angle of projection to the horizontal to enable the shot to

clear the top of the wall. Also find the time lapsed when

the shot left the wall

UNIT-IV

7. a) A train moves with a uniform speed of

57.6Kmph along a straight level track. At a certain

instant, the engineer moves the throttle so as to increase

the fraction by 20 Percent. What distance x will the train

cover before acquiring a speed of 72Kmph. If the

resistance to motion is constant and equal to 1/200 of the

weight of the train? 6

b) At the instant t=0, a locomotive starts to move with

uniformly accelerated speed along a circular curve of

radius r = 600m and acquires by the end of the first 60 s

of motion a speed equal to 24 kmph. Find the tangential

and normal acceleration at the instant t = 30S

6

OR





8. a) Prove that, if the ends A and B of a bar AB of

length 2l are constrained to move along the y-and x-

axis respectively its mid-point ‘c’ describes a circle of

radius ‘l’ with centre at ‘O’ while any intermediate point

‘D’ describes an ellipse with major and minor semi

axes l+b and l-b, respectively

b) Racing cars travel around a circular track of

300m radius with a speed of 384 kmph. What angle

‘α’should the floor of the track make with the

horizontal in order to safeguard against skidding ? 6



UNIT-V

9. a) After the block in fig. Has moved 3m from

rest, the constant force ‘p’ is removed. Find the

velocity of the block when it returns to its initial

position v= 6.4 m









b) What is the value of normal acceleration . If the

path of a particle in a stright line? If the speed of a

particle along a curved path is constant, what is the

value of tangential acceleration ? 4





OR

10. a) A 0.12kg baseball is thrown with a velocity of

18M/s toward a batter. After being struck by the bat ,

the ball has a velocity of 48m/s directed as shown in

fig. Find the average force exerted on the ball if the

impact lasts for 0.02 sec









b) Explain the terms Plastic impact , Elastic impact ,

and Semi Elastic impact 4







http://zakkam.blogspot.com/

http://passbtechexams.blogspot.com/