This document is a tutor marked assignment for an engineering mechanics course. It contains 10 questions assessing students' understanding of topics covered during the course including forces, kinematics, centroids, moments of inertia, and static friction. Students are asked to calculate values, draw diagrams, locate centroids, and determine tensions, forces, and velocities related to various physical situations. All questions must be answered and submitted by July 31, 2012 for grading.

1. BTCM
TUTOR MARKED ASSIGNMENT
ET 202 (Part A)
ENGINEERING MECHANICS
Maximum Marks : 100
Weightage : 30%
Course Code : ET-202A
Last Date of Submission : July 31, 2012
Note : All questions are compulsory and carry equal marks. This assignment is based on all
Blocks of Engineering Mechanics.
Q.1 (a)
Two forces of 10 kg and 15 kg act simultaneously at a point. Find the resultant force,
if the angle between the two forces be (i) 30 o, (ii) 45o, (iii) 60o, (iv) 90o, and (v) 180o.
Draw the force diagram for each situation.
(b)
Find the angle between two equal force P, when their resultant is equal to (i) P, (ii) P/2,
(iii) 2 P, (iv) 3 P, and (v) √2 P. Draw the force diagram for each case.
Q.2 (a)
A particle is acted upon by three forces equal to 5 kg, 10 kg and 13 kg, along the sides
of an equilateral triangle taken in order. Find graphically the magnitude and direction of
the resultant force. Find the magnitude and direction of the resultant force if forces are
acting along the sides of right angle triangle when one of the angle is 45 o.
(b)
Four forces of 2, 2.5, 1, and 3 kg are acting simultaneously along straight lines OA, OB,
OC and OD, such that ∠ OAB = 40o, ∠ BOC = 100o and ∠ COD = 125o. Find graphically
the magnitude and direction of the resultant force.
Q.3 A body weighing 10 kg, is suspended by two strings AC and BC at the point C. The lengths of
the strings AC and BC are 3 metres and 4 metres respectively and the horizontal distance BC is
also 4 metres. Find the tensions in the strings AC and BC.
Q.4 (a)
(b)
A fly wheel of weight 200 N and diameter 20 cm is made to rotate at 10 rotation per
second. Determine the K.E. of the wheel. If the frictional couple at its bearing is 10 Nm,
determine the number of revolution it will make before coming to rest. If the frictional
couple at bearing is double, determine the numbers of revolutions it will make before
coming to rest.
A mass of 4 kg moving with a velocity of 10 m/sec along x direction follows another
mass of 10 kg moving with 5 m/sec in the same direction. Determine the final velocities
of the two masses (i) if e = 0.6, (ii) if the impact is fully plastic, determine also the loss in
KE, and (iii) the impact is perfectly elastic, determine the final velocities of the two
bodies.
Q.5 A metal rod A of 25 cm length expands by 0.05 cm when its temperature is raised from 0oC to
100oC. Another rod B of a different metal of length 40 cm expands by 0.04 cm for the same
rise in temperature. A third rod C of 50 cm length, made up of pieces of rod A and B placed
end to end, expands by 0.03 cm on heating from 0 oC to 50oC. Find the lengths of each portion
of the composite rod C.
Q.6 A shell of weight 7 kN is fired horizontally from a gun weighing 400 kN, with a velocity 450
m/sec. With what velocity will the gun recoil? What will be the average force of resistance to
bring it to rest in a distance of 2 meters.
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2. Q.7 (a)
Consider a simply supported beam subjected to a uniformly distributed load on the left
half of the span as shown in Figure 1.
A
B
4m
4m
Figure 1
Determine SF and BM diagrams for the beam and find the location of the magnitude of
maximum BM.
(b)
Find the forces in all the members of the truss shown in Figure 2.
6m
6m
A
3m
C
E
D
150 kN
3m
B
Figure 2
Q.8 A boy throws a ball so that it may just clean a wall 3.6 m high. The boy is at a distance of
4.8 m from the wall. The ball was found to hit the ground at a distance of 3.6 m on the other
side of the wall as shown in Figure 3. Find the least velocity with which the ball can be thrown.
B
3.6 m
V
α
O
X
A
4.8 m
3.6 m
Figure 3
Q.9
Locate the centroid for plane section shown in Figure 4 and determine the moment of inertia
about AB.
C
φ 2 cm
12 cm
4
cm
B
Hole
A
4 cm
4 cm
Figure 4
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3. Q.10 Calculate the force required, P, to cause a block of weight W1 to slide under the another block
of weight W2. What will be the tension in the string AB. W1 = 2000 N, W2 = 1000 N, µ = 0.3.
A
W2
P
W1
Figure 5
20
30o