⚙️ Basic Mechanical Engineering Solved Paper 2022
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B.Tech. I-Semester (Main) Exam - April/May 2022
Subject: Basic Mechanical Engineering
Code: 1FY3-07 / 1E3107
PART - A (Short Answer Questions)
Q.1 State the first law of thermodynamics.
The first law states that energy can neither be created nor destroyed; it can only transform from one form to another. For a closed system undergoing a thermodynamic cycle, net heat transfer equals net work done (dQ = dU + dW).
Q.2 What do you mean by slip in belt?
Slip is the relative motion between the belt and pulley rim caused by insufficient frictional grip, resulting in a reduction in driven pulley speed and transmission velocity ratio.
Q.3 Which pump require priming? What is the need for priming.
Centrifugal pumps require priming. Priming removes trapped air from the suction pipe and casing by filling them with liquid to ensure the impeller builds necessary suction head.
Q.4 Differentiate between brazing and soldering.
• Brazing: Joins metals using non-ferrous filler metal melted above 450°C without melting base metals.
• Soldering: Joins metals using lead-tin alloy filler melted below 450°C, producing lower joint strength.
• Soldering: Joins metals using lead-tin alloy filler melted below 450°C, producing lower joint strength.
Q.5 Mention the steps involved in designing of a part (Product).
1. Problem identification & requirements definition
2. Conceptual design & mechanism synthesis
3. Material selection & stress/load analysis
4. Detailed design, CAD modeling & manufacturing drawings
2. Conceptual design & mechanism synthesis
3. Material selection & stress/load analysis
4. Detailed design, CAD modeling & manufacturing drawings
Q.6 Differentiate between COP and efficiency of system.
• Efficiency (η): Ratio of work output to energy input (always less than 1 or 100%).
• COP (Coefficient of Performance): Ratio of desired heating/cooling effect to work input (can be greater than 1).
• COP (Coefficient of Performance): Ratio of desired heating/cooling effect to work input (can be greater than 1).
Q.7 Write two important properties of steam.
1. Dryness Fraction (x): Ratio of mass of dry steam to total mass of wet steam.
2. Specific Enthalpy: Total heat content stored per unit mass of steam at a given pressure.
2. Specific Enthalpy: Total heat content stored per unit mass of steam at a given pressure.
Q.8 List the four important properties of molding sand.
1. Permeability (Porosity)
2. Refractoriness
3. Green Strength (Cohesiveness)
4. Collapsibility
2. Refractoriness
3. Green Strength (Cohesiveness)
4. Collapsibility
Q.9 Give the example of any two alloys and state their application.
1. Brass (Copper + Zinc): Used in plumbing fittings, valves, electrical connectors, and decorative items.
2. High-Speed Steel (HSS): Used for high-speed cutting tools like drills, milling cutters, and lathe tools.
2. High-Speed Steel (HSS): Used for high-speed cutting tools like drills, milling cutters, and lathe tools.
Q.10 Mention the different fields of mechanical engineering.
Thermal and Fluid Power Engineering, Machine Design and Dynamics, Manufacturing & Production Technology, Robotics & Automation, Automotive Engineering, and Materials Engineering.
PART - B (Analytical / Problem Solving)
Q.1 Give the types of welding and explain any one type of welding with neat sketch.
Types of Welding:
• Fusion Welding: Arc Welding, Gas Welding, TIG/MIG Welding.
• Pressure/Solid State Welding: Resistance Welding, Forge Welding, Friction Welding.
Shielded Metal Arc Welding (SMAW):
An electric power source creates an arc between a flux-coated electrode and the base metal. The extreme heat melts the workpiece edges and filler rod. The flux coating decomposes to form protective gas shielding the molten pool from atmospheric contamination.
• Fusion Welding: Arc Welding, Gas Welding, TIG/MIG Welding.
• Pressure/Solid State Welding: Resistance Welding, Forge Welding, Friction Welding.
Shielded Metal Arc Welding (SMAW):
An electric power source creates an arc between a flux-coated electrode and the base metal. The extreme heat melts the workpiece edges and filler rod. The flux coating decomposes to form protective gas shielding the molten pool from atmospheric contamination.
Q.2 Compare the working of two stroke and four stroke internal combustion engine.
| Parameter | Two-Stroke Engine | Four-Stroke Engine |
|---|---|---|
| Power Cycle | 1 power stroke per 1 crankshaft revolution | 1 power stroke per 2 crankshaft revolutions |
| Port/Valve | Uses ports uncovered by piston | Uses intake/exhaust valves with camshaft |
| Weight & Compactness | Lighter, simpler, and compact design | Heavier, complex valve train mechanism |
| Efficiency | Lower thermal and fuel efficiency | Higher thermal efficiency and fuel economy |
Q.3 How is steam produced in a fire tube boiler. Explain with a neat figure.
Working of Fire Tube Boiler (e.g., Cochran Boiler):
- Combustion of fuel occurs on the grate inside the furnace.
- Hot combustion gases pass through horizontal fire tubes submerged inside a shell filled with water.
- Heat is transferred through tube walls into surrounding water, elevating its temperature to boiling point.
- Generated steam collects in the steam space at the top of the boiler drum.
Q.4 Discuss any five properties of engineering materials.
1. Ductility: Ability of material to be drawn into thin wires under tensile load.
2. Malleability: Capacity to be flattened into thin sheets under compressive forces.
3. Hardness: Resistance of a material to surface indentation, scratching, or abrasion.
4. Toughness: Ability of material to absorb energy and deform plastically before fracturing.
5. Elasticity: Power to regain original shape and dimensions upon removal of applied load.
2. Malleability: Capacity to be flattened into thin sheets under compressive forces.
3. Hardness: Resistance of a material to surface indentation, scratching, or abrasion.
4. Toughness: Ability of material to absorb energy and deform plastically before fracturing.
5. Elasticity: Power to regain original shape and dimensions upon removal of applied load.
Q.5 Write short notes on (i) Rolling (ii) Extrusion.
(i) Rolling: Metal-forming deformation process where a billet or slab passes between two opposing rotating cylinders to reduce cross-sectional thickness and create uniform plates, sheets, or structural shapes.
(ii) Extrusion: Manufacturing process where a heated metal billet is placed in a container and forced by a hydraulic ram through a shaped die opening to produce long components with fixed cross-sectional profiles.
(ii) Extrusion: Manufacturing process where a heated metal billet is placed in a container and forced by a hydraulic ram through a shaped die opening to produce long components with fixed cross-sectional profiles.
Q.6 Explain any one type of boiler with neat sketch.
Babcock & Wilcox Boiler (Water Tube Boiler):
- Construction: Consists of a longitudinal water and steam drum connected to inclined straight water tubes via uptake and downtake headers.
- Operation: Water circulates naturally through tubes. Hot flue gases from furnace pass over tubes redirected by baffles, efficiently vaporizing water into high-pressure steam stored in drum.
Q.7 Mention the difference between open and cross belt drive.
| Feature | Open Belt Drive | Cross Belt Drive |
|---|---|---|
| Direction of Rotation | Pulleys rotate in the same direction | Pulleys rotate in opposite directions |
| Arc of Contact | Smaller arc of contact | Larger arc of contact |
| Power Transmission | Less power capacity due to slip | Higher power capacity with less slip |
| Belt Rubbing & Wear | No belt surface rubbing | Belts rub against each other, increasing wear |
PART - C (Descriptive / Analytical / Design)
Q.1 List out major components of an automobile with their function.
1. Engine: Power plant converts chemical fuel energy into mechanical rotational power.
2. Clutch: Engages or disengages power transmission between engine crankshaft and gearbox.
3. Gearbox (Transmission): Provides required torque-speed ratios according to road conditions.
4. Propeller Shaft & Differential: Transmits rotary drive to rear wheels and allows varying wheel speeds on turns.
5. Braking System: Slows down or stops vehicle safely using friction forces.
6. Steering System: Controls directional control and wheel positioning of vehicle.
2. Clutch: Engages or disengages power transmission between engine crankshaft and gearbox.
3. Gearbox (Transmission): Provides required torque-speed ratios according to road conditions.
4. Propeller Shaft & Differential: Transmits rotary drive to rear wheels and allows varying wheel speeds on turns.
5. Braking System: Slows down or stops vehicle safely using friction forces.
6. Steering System: Controls directional control and wheel positioning of vehicle.
Q.2 Explain the different types of power transmission devices.
1. Belt Drives: Flexible drives used for medium-distance shafts (Flat belts, V-belts, Timing belts).
2. Rope Drives: Flexible drives using fiber/steel wire ropes for long-distance, high-power transmission.
3. Chain Drives: Positive flexible drives using roller chains and sprockets for short to medium distances without slippage.
4. Gear Drives: Rigid positive drives utilizing meshed tooth wheels for compact, high-precision power transmission between short shafts.
2. Rope Drives: Flexible drives using fiber/steel wire ropes for long-distance, high-power transmission.
3. Chain Drives: Positive flexible drives using roller chains and sprockets for short to medium distances without slippage.
4. Gear Drives: Rigid positive drives utilizing meshed tooth wheels for compact, high-precision power transmission between short shafts.
Q.3 Explain the working of air-conditioning system.
Working of Air-Conditioning System:
- Compression: Compressor pressurizes gaseous refrigerant into high-temperature vapor.
- Condensation: Condenser coil rejects indoor heat outside, converting vapor into liquid refrigerant.
- Expansion: Expansion valve reduces liquid pressure, dropping refrigerant temperature significantly.
- Evaporation: Evaporator coil absorbs indoor room heat, cooling indoor air blown across it while vaporizing refrigerant.
- Air Distribution: Filters clean room air while blower circulates conditioned air evenly.
Q.4 Describe forging process with neat sketches.
Forging Manufacturing Process:
Forging is a metal forming process where heated metal stock is shaped using compressive impact forces from hammers or presses.
Forging is a metal forming process where heated metal stock is shaped using compressive impact forces from hammers or presses.
- Open-Die Forging: Workpiece compressed between flat dies without enclosing metal completely.
- Closed-Die (Impression) Forging: Metal squeezed into contoured die cavities, producing intricate components like crankshafts, connecting rods, and gears.
- Advantages: Refines grain structure, removes internal voids, and provides high fatigue strength.
Q.5 With a suitable sketch explain the working of reciprocating pump.
Working of Single-Acting Reciprocating Pump:
A positive displacement pump that converts rotary motor motion into linear piston movement using crank-connecting rod mechanism.
A positive displacement pump that converts rotary motor motion into linear piston movement using crank-connecting rod mechanism.
- Suction Stroke: As piston moves away from cylinder head, partial vacuum forms. Pressure differential opens suction valve, drawing liquid through suction pipe into cylinder.
- Delivery Stroke: Piston reverses direction, compressing trapped fluid. Suction valve closes and delivery valve opens, driving pressurized liquid out through delivery pipe.