e.mechanics

ID.NO/SEAT NO.

MEHRAN UNIVERSITY OF ENGINEERING AND TECHNOLOGY, JAMSHORO SECOND TERM FIRST YEAR (1ND TERM) B.E. (CIVIL) REGULAR EXAMINATION 2010 OF 10-BATCH ENGINEERING MECHANICS

Dated: 23-11-2010

Time Allowed: 03 Hours.

Max.Marks-80.

NOTE.ATTEMPT ANY FIVE QUESTIONS.ALL QUESTIONS CARRY EQUAL MARKS. X IS YOUR ROLL NUMBER.ASSUME YOUR OWN DATA WHERE NECESSARY. Q.NO. (01 ) Define force and system of forces. state and prove the parallelogram law of forces. four forces 50,60,70 and (x+20) lbs. act on directions north to east, south, south to west and west respectively. Find the magnitude and direction of resultant.

(02) Define with neat sketches uniformly distributed and uniformly carrying loads. How these loads are converted into point loads. Find value of α and θ to maintain one equilibrium of system shown in fig(1) (03-a) A body is resting on a incline making an angle of 450 with the horizontal and is subjected to a vertical force of (1000+X)lbs acting down-wards and a force of (600+x)lbs inclined at 250 to the horizontal and towards right. Find the components of each force along X-Y axes oriented parallel and perpendicular to the incline.

(b) The resultant of two forces F1 and F2 is R. if F2 be doubled; the new resultant is perpendicular to F1. Prove that F2=R (04) What do you understand by moment and momentum? In Figure 2. If the moment of force p is (4200+x) ft-lb about c, find the moment of P about D and B. if

the moment of force F about B is (8000+X) ft-lb, find also the moment of F about A and D.

(05-a) Find the greatest and the least resultant of two forces and their angles having magnitude of 250N and 280N respectively.

(b) A 50N horizontal beam of 20m has been fixed from right end and two forces of (450+x)N and 500N loads applied downward inclined at 300 at center and on the other end. Determine the resultant moment at the fixed end. Neglect the support reactions.

(06-a) a stone is dropped from top of building (100+X)m high. Another stone is projected upward at the same time, from the foot of the building and meets the first stone at height of 18 m. find the velocity with which the second stone is projected upwards. (b) The piston of a steam engine moves with simple harmonic motion. The crank rotates at (120+0.1X) r.p.m. and the stroke length is 2 meters. Find the velocity and acceleration of the piston, when it is at a distance of 0.75 meter from the (a)Extreme position

(b)The center

(07) A 45kg block slides a distance of 5 m along a Horizontal surface by a constant force p=(200+X)N inclined 300 to horizontal as shown in Figure 3. The coefficient of sliding friction is 0.30 a) Determine the normal and tangential forces the surface exerts on the block b) Determine the work done by each horizontal force that acts on the block as it slides 5m. c) Determine the total work done on the block. (08) Write short notes on any three of the followings: 1. Types of beams 2. Types of supports

3. Newton’s laws of motion 4. Simple harmonic motion 5. Friction Figure 1

Figure 2

Figure. 3

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