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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING SEMESTER I/II • EXAMINATION SUMMER- 2017
Subject Code: 310030 Date: 07- 06- 2017
Subject Name: Engineering Mechanics
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Each question carry equal marks (14 marks)
Q.1


State and explain parallelogram law of forces.
Define the following terms
Dynamics Scalar quantity Vector quantity
07




07

Two tensile forces acting at an angle 120º between them. The bigger force is 40 kN. The resultant is perpendicular to the smaller force. Find the smaller force resultant force.


120º 40 kN

Q.2

Differentiate between moment and couple.
Explain different types of load on beam.
07




07

ABCD is a square of 2 m side. Forces 8 kN 12 kN 12 kN 10 kN are acting respectively along DA, AB, BC and BD. Find out magnitude and direction of the resultant and will fall in which quadrant


ABCD 2 m 8 kN 12 kN 12 kN 10 kN DA, AB, BC BD

OR

A body of 10 kN is suspended by two strings of length of 50 cm and 120 cm attached to two hooks in horizontal ceilings 130 cm apart. Find the tension in both strings.
07

130 cm 50 cm 120 cm 10 kN
Q.3

A projectile projected from ground attains the maximum height of 10 m and horizontal range of 50 m. Calculate the time of flight.
07
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10 50
07

Explain V-T diagram. Also draw V-T diagram for a body moving with uniform velocity, uniform acceleration, and uniform retardation.
Explain Centripetal and Centrifugal force.


V-T V-T


OR
Q.3

A flywheel is rotating at 300 RPM comes to 60 RPM in 30 seconds. How many revolutions the wheel must have turn during this tmime
07


300 RPM 30 60 RPM
07

A stone of mass 0.1kg is tied at the end of a string 1.0 m long. The stone is whirled in a vertical plane. If the strength of string in tension is 78.5 calculate the maximum velocity of stone that can be whirled


0.1kg 1 m 78.5 N

Q.4

A beam ABC is 8 m long. Support A is hinged while support B is Roller one. AB is 6 m and portion BC is overhanging. Load of 4 kN/m is acting from support A for 2 m length of beam and a load of 2 kN is acting at 4 m support A. Load of 3 kN is acting at C. Calculate reactions at A and B.
07


ABC 8 A B AB 6 BC 4 kN/m A 2 2 kN A 4 3 kN C
07

An I-section has top flange 20 cm X 2 cm web 30 cm X 2 cm and bottom flange 40 cm X 4 cm . Find centroid of the section.


20 cm X 2 cm 30 cm X 2 cm 40 cm X 4 cm

OR
Q.4

Explain Law of conservation of energy
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07

A block weighing 500 N is just on the point of moving up the plane by 300 N force applied parallel to the plane. The surface is inclined at an angle 30º with horizontal. Find the coefficient of friction between block and the surface.


500 N 300 N

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30º
Q.5

Define Simple machine Mechanical advantage Velocity ratio
Efficiency Ideal machine Reversible machine
Self locking machine.
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07

In a lifting machine an effort of 8 N can lift a load of 300 N and an effort of 12 N can lift a load of 700 N. Find the law of machine and effort required to lift a load of 2 kN.


8 N 300 N 12 N 700 N 2 kN

OR
Q.5

Enlist the different simple machines and give their equation for velocity ratio.
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07

The following forces are acting at a point.
500 N force towards North-East.
400 N force towards East.
250 N force at 30º West of North.
300 N forces at 60º South of West.
Find magnitude and direction of the resultant.



500 N
400 N
250 N 30º
300 N 60º