ME-503-B Dynamics of Machine - Dec 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDraw and explain a turning moment diagram and discuss the significance of mean torque and fluctuations.
   How to answer

   • Define turning moment / crank-effort diagram: torque vs crank angle
   • Sketch for single/multi-cylinder engine with mean torque line
   • Explain excess energy areas above/below mean line
   • Significance of mean torque for power and fluctuation for flywheel design
2. 7 Marks
   bExplain how a flywheel controls speed fluctuations in an engine.
   How to answer

   • Function of flywheel as energy reservoir
   • Absorbs excess energy when supply > demand, releases when deficit
   • Relation $\Delta E = I\omega^2 C_s$ to limit speed fluctuation
   • Flywheel does not control mean speed, only cyclic fluctuation
3. 7 Marks
   aExplain how the energy fluctuation and coefficient of fluctuation of speed are determined from the turning moment diagram.
   How to answer

   • Identify max/min energy points on turning moment diagram
   • Fluctuation of energy $\Delta E$ = max excess area
   • Coefficient of fluctuation $C_s = (N_1-N_2)/N$
   • Relation $\Delta E = I\omega^2 C_s$ for flywheel sizing
4. 7 Marks
   bExplain the characteristics of centrifugal governors such as sensitivity, stability, isochronism, and effort with neat sketches.
   How to answer

   • Define sensitivity, stability, isochronism, effort/power
   • Sketch sleeve lift vs speed curves for each characteristic
   • Explain stable vs unstable and isochronous condition
   • Role of friction and controlling force on performance
5. 7 Marks
   aExplain hunting in centrifugal governors. Discuss the causes, effects and methods of prevention.
   How to answer

   • Define hunting as repeated over-correction of sleeve
   • Causes: excessive sensitivity, friction, lag, large sleeve movement
   • Effects: speed oscillation, wear, instability
   • Prevention: damping, friction control, stable design
6. 7 Marks
   bDerive the controlling force equation for a gravity controlled centrifugal governor.
   How to answer

   • Consider Watt/Porter type gravity-controlled governor geometry
   • Resolve forces: centrifugal force, weight, sleeve load
   • Equilibrium moment about pivot to get $F_c$ vs radius
   • Obtain controlling force equation $F_c = a\cdot r + b$ form
7. 7 Marks
   aDescribe balancing of rotating masses in the same plane using graphical and analytical methods.
   How to answer

   • Condition for balance: vector sum of $m r$ and $m r l$ zero
   • Analytical method: resolve $m_i r_i \cos\theta_i$, $m_i r_i \sin\theta_i$
   • Graphical method: force polygon and couple polygon closure
   • Determine magnitude and angular position of balance mass
8. 7 Marks
   bExplain the balancing of multi-cylinder engines including in-line engines and explain the Lacnchester balancing technique.
   How to answer

   • Primary and secondary forces/couples in multi-cylinder engines
   • Balancing conditions for in-line engines
   • Principle of Lanchester balancer with two counter-rotating masses
   • Cancellation of reciprocating unbalance
9. 7 Marks
   aA uniform disc of diameter $300\text{ mm}$ and of mass $5\text{ kg}$ is mounted on one end of an arm of length $600\text{ mm}$. The other end of the arm is free to rotate in a universal bearing. If the disc rotates about the arm with a speed of $300\text{ r.p.m.}$ clockwise, looking from the front, with what speed will it process about the vertical axis?
   How to answer

   • Calculate mass moment of inertia of disc $I = mr^2/2$
   • Gyroscopic couple = weight moment: $I\omega_s \omega_p = mg l$
   • Convert spin speed 300 r.p.m. to rad/s
   • Solve for precession speed $\omega_p$ about vertical axis
10. 7 Marks
    bDefine clutch. Its type and explain cone clutch with neat sketch.
    How to answer

    • Define clutch and its function in power transmission
    • Types: plate, cone, centrifugal, etc.
    • Construction and working of cone clutch with axial engagement
    • Neat labelled sketch with advantages
11. 7 Marks
    aA single plate clutch, with both sides effective, has outer and inner diameters $300\text{ mm}$ and $200\text{ mm}$ respectively. The maximum intensity of pressure at any point in the contact surface is not to exceed $0.1\text{N/mm}^2$. If the coefficient of friction is $0.3$, determine the power transmitted by a clutch at a speed $2500\text{ r.p.m.}$
    How to answer

    • Use uniform wear theory: $p r = $ constant, $p_{max}$ at inner radius
    • Find mean radius $R = (D+d)/4$ and axial force $W$
    • Torque $T = n \mu W R$ with $n=2$ for both sides
    • Power $P = 2\pi N T/60$
12. 7 Marks
    bDefine lubrication in bearing. What do you understand by boundary and fluid film lubrication?
    How to answer

    • Define lubrication purpose in bearings
    • Boundary lubrication: thin adsorbed film, metal contact
    • Fluid film lubrication: thick hydrodynamic film, no contact
    • Comparison with examples and sketch of regimes
13. 7 Marks
    aA torsion dynamometer is fitted to a propeller shaft of a marine engine. It is found that the shaft twists $2^\circ$ in a length of $20$ meters at $120$ r.p.m. If the shaft is hollow with $400\text{ mm}$ external diameter and $300\text{ mm}$ internal diameter, find the power of the engine. Take modulus of rigidity for the shaft material as $80\text{ GPa}$.
    How to answer

    • Torsion formula $T/J = G\theta/L$ to find torque
    • Polar moment $J = \pi(D^4-d^4)/32$ for hollow shaft
    • Convert $2^\circ$ twist and 20 m length to consistent units
    • Power $P = 2\pi N T/60$
14. 7 Marks
    bDescribe the working of band and block break with the help of neat sketch.
    How to answer

    • Construction: flexible band/blocks on brake drum
    • Working: tightening band increases frictional torque
    • Differential action for clockwise/anticlockwise
    • Neat sketch with lever, pivot and drum
15. 7 Marks
    aWhat do you understand by Cam? Explain its working principle with neat sketch.
    How to answer

    • Define cam and follower as higher pair mechanism
    • Working: rotary cam gives prescribed follower motion
    • Types of cams/followers and motion curves
    • Neat sketch of plate cam with follower
16. 7 Marks
    bWhat is the function of governor? How does it differ from flywheel?
    How to answer

    • Function of governor: regulate mean speed with load variation
    • Function of flywheel: limit cyclic fluctuation within cycle
    • Governor controls fuel supply, flywheel stores energy
    • Tabular comparison of action, time scale and control