2026 question paper
Dynamics of Machinery
28 questions
1(a). In force analysis of a mechanism, inertia force is generally considered to act: (i) In the direction of acceleration (ii) Opposite to the acceleration (iii) Perpendicular to acceleration (iv) Along the velocity.20262m
Module 1: Force Analysis of Mechanism
View this question on its own page →In force analysis of a mechanism, inertia force is generally considered to act: (i) In the direction of acceleration (ii) Opposite to the acceleration (iii) Perpendicular to acceleration (iv) Along the velocity.
1(b). A turning moment diagram represents the variation of: (i) Power with time (ii) Torque with crank angle (iii) Speed with time (iv) Acceleration with displacement.20262m
Module 2: Turning Moment Diagram
View this question on its own page →A turning moment diagram represents the variation of: (i) Power with time (ii) Torque with crank angle (iii) Speed with time (iv) Acceleration with displacement.
1(c). Coefficient of fluctuation of speed is defined as: (i) (Nmax + Nmin)/Nmean (ii) (Nmax − Nmin)/Nmean (iii) Nmean/Nmax (iv) Nmax/Nmin.20262m
Module 2: Turning Moment Diagram
View this question on its own page →Coefficient of fluctuation of speed is defined as: (i) (Nmax + Nmin)/Nmean (ii) (Nmax − Nmin)/Nmean (iii) Nmean/Nmax (iv) Nmax/Nmin.
1(d). For a knife-edge follower, the cam profile is the same as the: (i) Pitch curve (ii) Base circle (iii) Prime circle (iv) Pitch circle.20262m
Module 3: Cams
View this question on its own page →For a knife-edge follower, the cam profile is the same as the: (i) Pitch curve (ii) Base circle (iii) Prime circle (iv) Pitch circle.
1(e). A roller follower is preferred over a knife-edge follower mainly because it: (i) Has higher friction (ii) Reduces wear and friction (iii) Requires no cam (iv) Cannot transmit motion.20262m
Module 3: Cams
View this question on its own page →A roller follower is preferred over a knife-edge follower mainly because it: (i) Has higher friction (ii) Reduces wear and friction (iii) Requires no cam (iv) Cannot transmit motion.
1(f). In an aircraft, gyroscopic effects are associated with: (i) Pitching, yawing and rolling (ii) Only vertical translation (iii) Only fuel flow (iv) Only engine temperature.20262m
Module 4: Analysis of Gyroscopic Motion
View this question on its own page →In an aircraft, gyroscopic effects are associated with: (i) Pitching, yawing and rolling (ii) Only vertical translation (iii) Only fuel flow (iv) Only engine temperature.
1(g). Partial balancing is particularly important in: (i) Steam turbines (ii) Locomotives (iii) Electric motors (iv) Centrifugal pumps.20262m
Module 5: Effects of Inertia of Reciprocating Masses on Engine Frame
View this question on its own page →Partial balancing is particularly important in: (i) Steam turbines (ii) Locomotives (iii) Electric motors (iv) Centrifugal pumps.
1(h). The purpose of balancing reciprocating masses is to: (i) Increase engine temperature (ii) Reduce unbalanced forces and couples (iii) Increase friction (iv) Reduce fuel supply.20262m
Module 5: Effects of Inertia of Reciprocating Masses on Engine Frame
View this question on its own page →The purpose of balancing reciprocating masses is to: (i) Increase engine temperature (ii) Reduce unbalanced forces and couples (iii) Increase friction (iv) Reduce fuel supply.
1(i). In viscous damping, the damping force is proportional to: (i) Displacement (ii) Velocity (iii) Acceleration (iv) Mass.20262m
Module 6: Mechanical Vibrations
View this question on its own page →In viscous damping, the damping force is proportional to: (i) Displacement (ii) Velocity (iii) Acceleration (iv) Mass.
1(j). The ratio of actual damping coefficient to critical damping coefficient is called: (i) Frequency ratio (ii) Damping ratio (iii) Transmissibility ratio (iv) Amplitude ratio.20262m
Module 6: Mechanical Vibrations
View this question on its own page →The ratio of actual damping coefficient to critical damping coefficient is called: (i) Frequency ratio (ii) Damping ratio (iii) Transmissibility ratio (iv) Amplitude ratio.
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2(a). What is the difference between piston effort, crank effort and crank-pin effort?20267m
Module 1: Force Analysis of Mechanism
View this question on its own page →What is the difference between piston effort, crank effort and crank-pin effort?
2(b). A connecting rod is suspended from a point 25 mm above the centre of the small end, and 650 mm above its centre of gravity, its mass being 37.5 kg. When permitted to oscillate, the time period is found to be 1.87 seconds. Find the dynamically equivalent system constituted of two masses, one of which is located at the small-end centre.20267m
Module 1: Force Analysis of Mechanism
View this question on its own page →A connecting rod is suspended from a point 25 mm above the centre of the small end, and 650 mm above its centre of gravity, its mass being 37.5 kg. When permitted to oscillate, the time period is found to be 1.87 seconds. Find the dynamically equivalent system constituted of two masses, one of which is located at the small-end centre.
3(a). Define fluctuation of energy and coefficient of fluctuation of energy. Derive the expression for the coefficient of fluctuation of energy using the turning moment diagram.20267m
Module 2: Turning Moment Diagram
View this question on its own page →Define fluctuation of energy and coefficient of fluctuation of energy. Derive the expression for the coefficient of fluctuation of energy using the turning moment diagram.
3(b). The turning moment diagram for a petrol engine is drawn to these scales: turning moment, 1 mm = 5 N·m; crank angle, 1 mm = 1°. The diagram repeats itself at every half revolution of the engine. The areas above and below the mean turning moment line taken in turn are 295, 685, 40, 340, 960, 270 mm². The rotating parts are equivalent to a mass of 36 kg at a radius of gyration of 150 mm. Determine the coefficient of fluctuation of speed when the engine runs at 1800 r.p.m.20267m
Module 2: Turning Moment Diagram
View this question on its own page →The turning moment diagram for a petrol engine is drawn to these scales: turning moment, 1 mm = 5 N·m; crank angle, 1 mm = 1°. The diagram repeats itself at every half revolution of the engine. The areas above and below the mean turning moment line taken in turn are 295, 685, 40, 340, 960, 270 mm². The rotating parts are equivalent to a mass of 36 kg at a radius of gyration of 150 mm. Determine the coefficient of fluctuation of speed when the engine runs at 1800 r.p.m.
4(a). A cam drives a flat reciprocating follower as follows: during the first 120° rotation of the cam, the follower moves outwards through a distance of 20 mm with simple harmonic motion. The follower dwells during the next 30° of cam rotation. During the next 120° of cam rotation, the follower moves inwards with simple harmonic motion. The follower dwells for the last 90° of cam rotation. The minimum radius of the cam is 25 mm. Draw the profile of the cam.20267m
Module 3: Cams
View this question on its own page →A cam drives a flat reciprocating follower as follows: during the first 120° rotation of the cam, the follower moves outwards through a distance of 20 mm with simple harmonic motion. The follower dwells during the next 30° of cam rotation. During the next 120° of cam rotation, the follower moves inwards with simple harmonic motion. The follower dwells for the last 90° of cam rotation. The minimum radius of the cam is 25 mm. Draw the profile of the cam.
4(b). Draw the displacement, velocity and acceleration diagrams for a follower when it moves with uniform acceleration and retardation. Derive the expressions for velocity and acceleration during outstroke and return stroke.20267m
Module 3: Cams
View this question on its own page →Draw the displacement, velocity and acceleration diagrams for a follower when it moves with uniform acceleration and retardation. Derive the expressions for velocity and acceleration during outstroke and return stroke.
5(a). An aeroplane makes a complete half circle of 50 metres radius towards left when flying at 200 km/h. The rotary engine and propeller have a mass of 400 kg with radius of gyration 300 mm. The engine runs at 2400 r.p.m. clockwise when viewed from the rear. Find the gyroscopic couple on the aircraft and state its effect. What is the effect if the aeroplane turns right instead?20267m
Module 4: Analysis of Gyroscopic Motion
View this question on its own page →An aeroplane makes a complete half circle of 50 metres radius towards left when flying at 200 km/h. The rotary engine and propeller have a mass of 400 kg with radius of gyration 300 mm. The engine runs at 2400 r.p.m. clockwise when viewed from the rear. Find the gyroscopic couple on the aircraft and state its effect. What is the effect if the aeroplane turns right instead?
5(b). What do you understand by gyroscopic couple? Explain the application of gyroscopic principles to aircraft.20267m
Module 4: Analysis of Gyroscopic Motion
View this question on its own page →What do you understand by gyroscopic couple? Explain the application of gyroscopic principles to aircraft.
6(a). For a two-cylinder locomotive with cranks at 90°: reciprocating mass per cylinder = 300 kg; crank radius = 0.3 m; driving wheel diameter = 1.8 m; distance between cylinder centre lines = 0.65 m; distance between driving wheel central planes = 1.55 m. Determine (i) the fraction of reciprocating masses to be balanced if hammer blow is not to exceed 46 kN at 96.5 km/h, (ii) variation in tractive effort, and (iii) maximum swaying couple.20267m
Module 5: Effects of Inertia of Reciprocating Masses on Engine Frame
View this question on its own page →For a two-cylinder locomotive with cranks at 90°: reciprocating mass per cylinder = 300 kg; crank radius = 0.3 m; driving wheel diameter = 1.8 m; distance between cylinder centre lines = 0.65 m; distance between driving wheel central planes = 1.55 m. Determine (i) the fraction of reciprocating masses to be balanced if hammer blow is not to exceed 46 kN at 96.5 km/h, (ii) variation in tractive effort, and (iii) maximum swaying couple.
6(b). Explain partial balancing of locomotives and derive the expression for hammer blow.20267m
Module 5: Effects of Inertia of Reciprocating Masses on Engine Frame
View this question on its own page →Explain partial balancing of locomotives and derive the expression for hammer blow.
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7(a). A single-degree damped vibrating system has mass 7.5 kg and makes 24 free oscillations in 14 seconds. The amplitude reduces to 0.25 of its initial value after five oscillations. Determine (i) spring stiffness, (ii) logarithmic decrement, and (iii) damping factor (system damping/critical damping).20267m
Module 6: Mechanical Vibrations
View this question on its own page →A single-degree damped vibrating system has mass 7.5 kg and makes 24 free oscillations in 14 seconds. The amplitude reduces to 0.25 of its initial value after five oscillations. Determine (i) spring stiffness, (ii) logarithmic decrement, and (iii) damping factor (system damping/critical damping).
7(b). A mechanical vibrating system has mass 8 kg and equivalent spring stiffness 5.4 N/mm. A dashpot exerts a force of 40 N when the mass velocity is 1 m/s. Find (i) critical damping coefficient, (ii) damping factor, (iii) logarithmic decrement, and (iv) ratio of two consecutive amplitudes.20267m
Module 6: Mechanical Vibrations
View this question on its own page →A mechanical vibrating system has mass 8 kg and equivalent spring stiffness 5.4 N/mm. A dashpot exerts a force of 40 N when the mass velocity is 1 m/s. Find (i) critical damping coefficient, (ii) damping factor, (iii) logarithmic decrement, and (iv) ratio of two consecutive amplitudes.
8(a). Explain the principle of vibration isolation and transmissibility in mechanical vibration systems. Derive the expression for the transmissibility ratio.20267m
Module 6: Mechanical Vibrations
View this question on its own page →Explain the principle of vibration isolation and transmissibility in mechanical vibration systems. Derive the expression for the transmissibility ratio.
8(b). Explain the balancing of primary and secondary forces in reciprocating engines. Derive the conditions for complete balancing of primary and secondary forces.20267m
Module 5: Effects of Inertia of Reciprocating Masses on Engine Frame
View this question on its own page →Explain the balancing of primary and secondary forces in reciprocating engines. Derive the conditions for complete balancing of primary and secondary forces.
9(a). Write a short note on D’Alembert’s method for force analysis of mechanisms.20267m
Module 1: Force Analysis of Mechanism
View this question on its own page →Write a short note on D’Alembert’s method for force analysis of mechanisms.
9(b). Write a short note on reciprocating masses balancing by revolving mass.20267m
Module 5: Effects of Inertia of Reciprocating Masses on Engine Frame
View this question on its own page →Write a short note on reciprocating masses balancing by revolving mass.
9(c). Write a short note on the effect of the gyroscopic couple on a disc fixed at a certain angle to a rotating shaft.20267m
Module 4: Analysis of Gyroscopic Motion
View this question on its own page →Write a short note on the effect of the gyroscopic couple on a disc fixed at a certain angle to a rotating shaft.
9(d). Write a short note on underdamping, critical damping and overdamping.20267m
Module 6: Mechanical Vibrations
View this question on its own page →Write a short note on underdamping, critical damping and overdamping.
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