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JNTU B.Tech I Year ENGINEERING MECHANICS Previous Question Paper (August - 2018 - R15)

B.Tech | I Year | I-I | R15 | August - 2018

Answer PaperPaper Code: 121ACMaximum Marks: 75Time: 3 hours

Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.

Part A

125 marks
a
Define the term resultant of a force system.
2 marks

Answer

The resultant of a force system is a single force that produces the same external effect (in terms of translation and rotation) on a rigid body as the combined effect of all the individual forces in the original system.

b
Define the term free body diagram and state the importance of drawing such a diagram.
3 marks

Answer

A free body diagram (FBD) is a sketch of a body or a part of a body isolated from its surroundings, showing all external forces (applied loads and reaction forces) acting upon it. It is essential because it simplifies complex mechanical problems by isolating the body of interest, ensuring that all equilibrium equations are applied correctly by accounting for every force acting on that specific system.

c
Define the friction. How does it come into play?
2 marks

Answer

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d
What is the concept of limiting friction?
3 marks

Answer

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e
Define the terms centroid and centre of gravity.
2 marks

Answer

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f
What is polar moment of inertia? Explain.
3 marks

Answer

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g
Define normal and tangential acceleration in connection with curvilinear motion.
2 marks

Answer

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h
Write the equation of motion for the case general plane motion of a rigid body.
3 marks

Answer

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i
Write the Work –Energy equation of particles in translation.
2 marks

Answer

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j
What are the types of vibration? Give example for each.
3 marks

Answer

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Part B

2
Three forces of magnitude 150N, 300N and 500N are acting at the origin O (0,0,0) and are directed from the points A (3,2,4), B (3,-2,-4) and C (-1,-3,-4) respectively to the origin. Determine the magnitude of the resultant.
10 marks

Answer

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OR
3
Three bars, hinged at A and D and pinned at B and C, as shown in figure 1, form a four-linked mechanism. Determine the value of P that will prevent movement of bars.
10 marks

Answer

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4
Two blocks of weight W1 and W2 rest on a rough inclined plane and are connected by a short piece of string as shown in figure 2. If the coefficients of friction are µ1 = 0.2 and µ2 = 0.3, respectively, find the angle of inclination of the plane for which sliding will impend. Assume W1 = W2= 5 N.
10 marks

Answer

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OR
5
Referring to figure 3 the coefficient of the friction is as follows: 0.25 at the floor, 0.30 at the wall, and 0.20 between blocks. Find the minimum value of a horizontal force P applied to the lower block that will hold the system in equilibrium.
10 marks

Answer

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610 marks
a
Locate the centroid of a section as shown in Figure 4.
5 marks

Answer

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b
State and prove parallel axis theorem.
5 marks

Answer

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OR
7
Determine the mass moment of inertia of solid sphere of radius R about its any diametric axis.
10 marks

Answer

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8
An automobile enters a curved road at 30km/hr and then leaves at 48 km/hr. The curved road is in the form of quarter of a circle and has a length of 400 m. If the car travels at constant acceleration along the curve, calculate the resultant acceleration at both ends of the curve.
10 marks

Answer

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OR
9
A pulley weighs 500 N and has a radius of 0.75 m. A block weighing 400 N is supported by inextensible wire wound round the pulley. Determine the velocity of the block, 2 seconds after it is released from rest. Assume the motion is under constant acceleration.
10 marks

Answer

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10
A block of weight W starts from rest A as shown in figure 5. If the coefficient of friction between all surfaces of contact is 0.3, find the distance at which the block stops on the horizontal plane BC. Assume the magnitude of velocity at the end of slope is same as that of the beginning of the horizontal plane. Use work energy method.
10 marks

Answer

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OR
11
A particle moving with simple harmonic motion has velocities of 8 m/s and 4 m/s at the distance of 1 m and 2 m from the mean position. Determine (a) amplitude (b) time period (c) maximum velocity and (d) maximum acceleration of the particle.
10 marks

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About this paper

This page contains the question paper of ENGINEERING MECHANICS from JNTU for B.Tech CE I Year I-I, August - 2018, R15.

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