Past Questions

A blast furnace is used for the smelting of iron ore to produce iron. In this process, iron oxides (ore) are reduced by carbon monoxide (derived from coke) at very high temperatures. The resulting molten metal is saturated with carbon (typically 3.5% to 4.5%) and other impurities like silicon and phosphorus. This crude, high-carbon iron is called 'pig iron' because it is cast into molds (called pigs and sows) as it cools. Why other options are incorrect: - Cast iron (a): While pig iron is a type of cast iron, 'cast iron' usually refers to pig iron that has been remelted and refined for specific casting purposes. - Wrought iron (c): This is the purest form of iron (very low carbon), produced by removing carbon from pig iron through processes like puddling. - White iron (d): This is a specific type of cast iron where all carbon is present as cementite, usually achieved through rapid cooling or specific alloying, not as the primary direct output of a blast furnace.

In computer architecture, a 'word' is defined as the natural unit of data used by a particular processor design. It is a string of binary digits (bits) that the CPU can process as a single unit in one instruction cycle. The size of a word (e.g., 16-bit, 32-bit, or 64-bit) depends on the architecture of the processor. Why other options are incorrect: - a. byte: A byte is a specific unit of data, almost universally defined as 8 bits. While it is a unit, it is a fixed size, whereas a 'word' refers to the processor's native unit of operation. - b. bit: A bit (binary digit) is the smallest unit of data (0 or 1), not a 'string' of digits treated as a unit. - d. character: A character is a symbolic representation (like 'A' or '@') that is encoded using a specific number of bits (e.g., ASCII uses 7 or 8 bits), but it is a logical representation rather than a hardware-level processing unit.

Young's Modulus (E) is a measure of the stiffness of a solid material. It is defined as the ratio of tensile or compressive stress to the corresponding longitudinal strain. 1. Formula: E = Stress / Strain 2. Stress is defined as Force per unit Area. Its SI unit is Pascal (Pa), which is equivalent to Newton per square meter (N/m²) or Newton per square millimeter (N/mm²). 3. Strain is the ratio of change in length to original length (ΔL/L), making it a dimensionless quantity (it has no units). 4. Therefore, the unit of Young's Modulus is the same as the unit of stress. Evaluating the options: - (a) Newton: This is the unit of Force, not modulus. - (b) Newton/mm²: This is a standard unit of pressure/stress (1 N/mm² = 1 MPa), which is the correct unit for Young's Modulus. - (c) Newton/cm²: While technically a unit of stress, in the context of engineering and technical exams for Strength of Materials, N/mm² (MPa) is the standard convention used for material properties. - (d) Newton-cm²: This is a product of force and area, which does not represent stress or modulus.

A Gantt chart is a type of bar chart that illustrates a project schedule. In Industrial Engineering and Project Management, it is primarily used to plan and track the progress of tasks over time. 1. Why 'production schedule' is correct: A Gantt chart maps out the start and finish dates of various elements of a project or production process. It allows managers to see which tasks are happening simultaneously, the duration of each task, and the overall timeline for production, making it a fundamental tool for production scheduling. 2. Why 'determining selling price' is incorrect: Selling price is determined by cost analysis, market research, and profit margin calculations, not by a scheduling tool. 3. Why 'material handling layout' is incorrect: Material handling layouts are represented by flowcharts, string diagrams, or plant layout drawings (CAD), which focus on spatial arrangement and movement rather than time-based scheduling.

A peripheral device is any auxiliary device that connects to and works with the computer system but is not part of the core architecture (the CPU and primary memory). Examples include keyboards, mice, printers, and external scanners. Reasoning for other options: - a. Microprocessor: This is the 'brain' of the computer (the CPU) and is a fundamental internal part of the computer system. - c. Hardware: This is a general term encompassing all physical components of a computer, including both internal parts (like the motherboard) and external peripherals. It is too broad to be the specific answer. - d. Memory: This refers to the storage components (like RAM or ROM) which are essential internal parts of the computer's core architecture.

In arc welding (specifically Shielded Metal Arc Welding - SMAW), the electrode consists of a metal core wire coated with a chemical material known as 'flux'. 1. Why 'flux' is correct: The flux coating serves several critical purposes: it melts to create a gaseous shield (protecting the molten weld pool from atmospheric contamination like oxygen and nitrogen), it stabilizes the electric arc, and it forms a layer of slag on top of the weld to slow the cooling rate and prevent oxidation. 2. Why other options are incorrect: - 'Protective layer' is a general term, but the specific technical name for the coating material in welding is flux. - 'Binder' is a component within the flux coating that holds the flux chemicals to the core wire, but it is not the name of the coating itself. - 'Slag' is the byproduct (the solidified waste) that forms after the flux has reacted and cooled; it is the result of the coating, not the coating material itself.

Creep in a belt drive is the relative motion between the belt and the pulley surface. It occurs because the belt is subjected to different tensions at the tight side and the slack side of the drive. As the belt moves from the tight side to the slack side, it undergoes a slight contraction; conversely, as it moves from the slack side to the tight side, it undergoes a slight extension. This continuous cycle of extension and contraction causes the belt to 'slip' slightly relative to the pulley, even if there is no gross slippage. - Option (a) and (b) are incorrect because while the material properties (elasticity) allow creep to happen, the 'cause' of the motion is the tension differential, not the material itself. - Option (c) is incorrect because simple expansion (like thermal expansion) does not describe the cyclic process of creep during operation.

In thick cylinder hoop stress varies hyperbolically through thickness, longitudinal stress remains uniform.

CPM (Critical Path Method) and PERT (Program Evaluation and Review Technique) are the two primary network analysis techniques used in project management. 1. CPM (Critical Path Method) is an 'activity-oriented' technique. In CPM, the focus is on the activity itself (the work being performed), and the arrows in the network diagram represent the activities. It is typically used for deterministic projects where activity durations are known with certainty (e.g., construction projects). 2. PERT (Program Evaluation and Review Technique) is an 'event-oriented' technique. In PERT, the focus is on milestones or events (the start or completion of an activity), and the nodes represent these events. It is typically used for probabilistic projects where durations are uncertain (e.g., R&D projects). Therefore, option (c) is correct. Option (b) describes PERT, and options (a) and (d) are not standard classifications for these network techniques.

In a belt drive system, the belt speed (v) is the linear velocity of the belt. For a driver pulley with diameter D1 and angular velocity ω1, the belt speed is given by v = (π * D1 * N1) / 60, where N1 is the speed in RPM. However, the question asks for the proportionality of the 'belt speed' in the context of the relationship between the driver and driven pulleys. Usually, in these types of competitive exam questions, 'belt speed' refers to the speed ratio or the relative speed of the driven pulley (N2) compared to the driver pulley (N1). The fundamental equation for belt drives (assuming no slip) is: N1 * D1 = N2 * D2 Rearranging for the speed of the driven pulley (N2): N2 = N1 * (D1 / D2) However, if the question is interpreted as the ratio of the driven speed to the driver speed (the speed multiplier/reduction), it is D1/D2. But looking at the options provided, if we are looking for the relationship of the output speed relative to the input, and the options are structured as they are, we must evaluate the velocity ratio. Wait, let's re-evaluate: The linear belt speed (v) is the same for both pulleys (v = πD1N1 = πD2N2). If the question asks what the belt speed is proportional to in terms of the diameters for a given driven speed, v ∝ D2. If it asks for the speed ratio (N2/N1), it is D1/D2. Given the options provided in many technical exams for this specific question, there is often a confusion between 'belt speed' (linear) and 'driven pulley speed' (angular). If the question implies the ratio of the driven speed to the driver speed (N2/N1), the answer is D1/D2. If the question asks for the ratio of driver speed to driven speed (N1/N2), the answer is D2/D1. In the context of the MPSC 2010 paper, the intended answer for the speed ratio (Driver/Driven) is D2/D1. This represents the 'velocity ratio' (VR = N1/N2 = D2/D1).

Slag inclusion occurs during the casting process when non-metallic impurities (slag, oxides, or refractory particles) are trapped within the molten metal as it solidifies. Because these impurities are often carried into the bulk of the casting by the flow of the liquid metal, they typically end up embedded inside the body of the part, making it an internal defect. While slag can occasionally be found near the surface, it is fundamentally classified as an internal discontinuity or inclusion. Comparison with other options: - (a) Surface defects are those visible on the exterior, such as blowholes or scabs. - (c) Cracks are fractures caused by thermal stress or shrinkage, not by trapped foreign material. - (d) A notch is typically a geometric feature or a mechanical cut/defect on the surface, not a casting impurity.

Electro-discharge machining (EDM) is a non-traditional machining process that removes material through a series of rapidly recurring electrical sparks between an electrode (tool) and a conductive workpiece. For this process to occur effectively, both the tool and the workpiece must be submerged in a dielectric fluid. The dielectric fluid serves three primary purposes: 1) It acts as an electrical insulator until the breakdown voltage is reached, allowing the energy to build up before the spark occurs; 2) It cools the electrode and the workpiece to prevent thermal damage; and 3) It flushes away the eroded metal particles (debris) from the spark gap. Why other options are incorrect: - b. An abrasive slurry is used in Ultrasonic Machining (USM), not EDM. - c. A vacuum is not used as the primary medium in EDM because the fluid is necessary for cooling and flushing. - d. An electrolytic solution is used in Electrochemical Machining (ECM), where material is removed by anodic dissolution rather than thermal sparking.

Malleable iron is produced by the heat treatment (annealing) of white cast iron. In white cast iron, carbon is chemically combined as cementite (Fe3C), which makes the material hard and brittle. During the malleabilizing process, the cementite decomposes into iron and graphite. Unlike grey cast iron, where graphite forms sharp 'flakes' that act as stress concentrators, the graphite in malleable iron forms irregular, rounded clumps known as 'temper carbon' or 'nodular aggregates'. These rounded shapes reduce stress concentration, giving the material its characteristic ductility and toughness (malleability). Analysis of other options: - a. Cementite: This is the form of carbon in white cast iron; malleabilization is specifically designed to remove cementite. - b. Free carbon: While graphite is 'free carbon', this term is too general and does not describe the specific morphology required for malleable iron. - c. Flakes: This is the characteristic form of carbon in grey cast iron, which makes it brittle. - d. Nodular aggregates: This correctly describes the 'temper carbon' found in malleable iron.

A Woodruff key is a semi-circular (segmental) key that is embedded in a keyway of the shaft and the hub of the pulley or gear. It is specifically manufactured from a cylindrical disc, resulting in a cross-section that is a segment of a circle. This design allows the key to be automatically centered and is particularly useful for tapered shafts. Analysis of other options: - b. Feather key: A key that allows the hub to slide axially along the shaft while transmitting torque. - c. Flat saddle key: A key that is flat on the top and curved on the bottom to fit a shaft without a keyway being cut into the shaft itself. - d. Gib head key: A square key with a head at one end to facilitate easy removal using a drift or hammer.

To determine which factor is independent of a sales forecast, we must analyze the relationship between demand forecasting and operational management: 1. **Sales Forecast** is an estimate of future demand. It serves as the primary input for planning how much to produce and what resources are needed. 2. **Inventory Control (Option b):** This is directly dependent on sales forecasts. To avoid stockouts or overstocking, a company must know the expected demand to determine safety stock levels and reorder points. 3. **Production Planning (Option c):** This is the process of deciding how to allocate resources to meet demand. It is fundamentally driven by the sales forecast (e.g., Aggregate Production Planning). 4. **Production Control (Option d):** This involves monitoring the actual production process to ensure it aligns with the plan. Since the plan itself is based on the sales forecast, production control is indirectly dependent on it to ensure the right quantity is produced at the right time. 5. **Productivity (Option a):** Productivity is a measure of efficiency (Output / Input). It describes how well a system converts resources into products regardless of the volume of demand. For example, if a machine produces 10 units per hour, its productivity is 10 units/hr whether the sales forecast is for 1,000 units or 10,000 units. While a company may strive to improve productivity to meet a high forecast, the *metric* of productivity itself is an internal efficiency measure and is independent of the external sales forecast.

In the context of Strength of Materials, the 'moment of inertia' for a solid circular shaft usually refers to the Area Moment of Inertia (also known as the Second Moment of Area) about its centroidal axis, which is critical for calculating bending stress. 1. The formula for the Area Moment of Inertia (I) of a circle with radius 'r' is I = (πr^4)/4. 2. Since the diameter 'd' is twice the radius (d = 2r), we substitute r = d/2 into the formula: I = (π * (d/2)^4) / 4 I = (π * (d^4 / 16)) / 4 I = πd^4 / 64. Comparison with other options: - Option (a) πd^4/32 is the Polar Moment of Inertia (J), which is used for calculating torsional shear stress (J = 2I). - Option (c) and (d) are mathematically incorrect for a standard solid circular cross-section.

An idler pulley is a pulley that does not transmit power but is used for specific mechanical purposes in a belt drive system. Its primary functions are: 1) To maintain proper tension in the belt to prevent slippage (acting as a tensioner), and 2) To increase the angle of wrap (arc of contact) on the driving or driven pulley to improve grip and power transmission. While an idler can technically change the direction of a belt, its fundamental engineering purpose in the context of belt drive efficiency is to ensure the belt remains taut (applying tension). Option (a) is a secondary effect, but (b) is the primary functional purpose. Option (c) is incorrect because the velocity ratio is determined by the diameters of the driving and driven pulleys, not by the idler pulley.

A slider-crank chain consists of three turning pairs and one sliding pair. An inversion is obtained by fixing different links of the kinematic chain. 1. **Whitworth quick return mechanism**: This is an inversion of the slider-crank chain where the crank is fixed (or a specific link arrangement is used to create a quick return motion), allowing the slider to move in a straight line while the tool oscillates. 2. **Hand pump**: In a hand pump, the cylinder (the sliding part's guide) is fixed. This is a classic inversion of the slider-crank mechanism where the frame/cylinder is the fixed link. 3. **Oscillating cylinder engine**: In this mechanism, the crank is fixed, and the cylinder itself is allowed to oscillate. This is another recognized inversion of the slider-crank chain. Since all three listed mechanisms are derived from the inversion of the slider-crank chain, the correct option is 'All of them'.

Nodular iron, also known as ductile iron, is a type of cast iron where the graphite exists as spherical nodules (spheroids) rather than flakes. This is achieved by adding a nodulizing agent, typically magnesium or cerium, to the molten metal before casting. The spherical shape of the graphite minimizes stress concentrations within the metal matrix, which significantly improves the material's ductility, toughness, and tensile strength compared to grey cast iron. Analysis of other options: - a. Cementite: This is a hard, brittle intermetallic compound (Fe3C) found in white cast iron, not the form of graphite in nodular iron. - b. Free carbon: While graphite is a form of free carbon, this term is too general and does not describe the specific morphology (shape) characteristic of nodular iron. - c. Flakes: Graphite in the form of flakes is the defining characteristic of Grey Cast Iron, which makes the material brittle.

Fatigue failure typically initiates at the surface of a component due to stress concentrations or surface defects. To increase the fatigue limit, the surface must be strengthened or placed under compressive residual stress. 1. **Cold working (Option a):** Processes like cold rolling or drawing increase the yield strength and hardness of the material through strain hardening, which generally improves fatigue resistance. 2. **Shot peening (Option c):** This process involves bombarding the surface with small spherical shots, creating a layer of compressive residual stress. Since fatigue cracks usually initiate and propagate under tensile stress, this compressive layer significantly increases the fatigue limit. 3. **Surface decarburisation (Option b):** This is a process where carbon is lost from the surface of the steel during heating. This results in a softer, lower-strength surface layer (ferrite) compared to the core. A softer surface is more prone to crack initiation and reduces the overall fatigue strength of the component. Therefore, decarburisation is detrimental to fatigue life, not a method to increase it.

To determine which alloy does not contain copper, let's analyze the composition of each option: 1. **Delta metal**: This is a high-strength alloy primarily composed of Copper (Cu), Silver (Ag), and Gold (Au). It contains copper. 2. **Monel metal**: This is a group of nickel-copper alloys. The most common form is approximately 67% Nickel (Ni) and 30% Copper (Cu). It contains copper. 3. **Nichrome**: This is an alloy consisting primarily of Nickel (Ni) and Chromium (Cr), often with small amounts of iron. It is widely used in heating elements due to its high electrical resistance and oxidation resistance. It does NOT contain copper. 4. **Silicon bronze**: As the name suggests, it is a type of bronze. Bronze is an alloy of Copper (Cu) and Tin (Sn), and silicon bronze specifically adds silicon to improve corrosion resistance and strength. It contains copper. Therefore, Nichrome is the only alloy among the choices that does not have copper as a constituent.

A rope brake dynamometer is used to measure the brake power of an engine. It works on the principle of friction between a rope and a drum. The rope is wrapped around a drum, and a load is applied to the free end of the rope. The braking torque is generated by the frictional force between the rope and the surface of the drum. For the device to function accurately, a high and consistent coefficient of friction is required to translate the tension in the rope into a measurable braking torque. If a lubricant (such as oil, water, or grease) were used, it would significantly reduce the coefficient of friction, causing the rope to slip excessively and making it impossible to apply the necessary braking load or obtain an accurate power measurement. Therefore, the rope brake dynamometer is designed to operate dry, and no lubricant is required.

Cemented carbides (also known as tungsten carbide) are composite materials consisting of hard ceramic particles (typically Tungsten Carbide, WC) bonded together by a metallic binder. Cobalt (Co) is the most widely used binding material because it has excellent wetting properties with tungsten carbide, allowing it to flow around the hard particles during the liquid-phase sintering process, creating a dense, strong, and tough composite. Why other options are incorrect: - Nickel (b): While nickel can be used as a binder (especially for improved corrosion resistance), cobalt is the standard and primary binding material for general-purpose cemented carbides. - Vanadium (c): Vanadium is often added in small quantities as a grain growth inhibitor to maintain a fine microstructure, but it does not act as the primary binding matrix. - Carbon (d): Carbon is a constituent of the carbide phase itself (e.g., WC), not the metallic binder that holds the carbide grains together.

In computer architecture, memory (specifically RAM) is organized as a linear array of storage units. Each unit is referred to as a 'memory location'. Each of these locations is assigned a unique numerical value known as an 'address', which allows the CPU to identify and access specific data. Why other options are incorrect: - a. addresses: An address is the numerical identifier used to find a location; memory is not divided into addresses, but rather locations that HAVE addresses. - b. codes: Codes refer to the instructions or data representations (like binary or ASCII), not the physical or logical divisions of memory storage. - d. cells: While 'cell' is sometimes used informally, 'location' is the standard technical term in computer fundamentals to describe the addressable units of memory.

The Maximum Principal Stress Theory, also known as Rankine's Theory, states that failure occurs when the maximum principal stress in a complex stress system reaches the yield stress (or ultimate stress) of the material in a simple tension test. 1. **Brittle Materials**: Brittle materials (like cast iron or stone) typically fail due to sudden fracture when the normal stress reaches a critical limit, without significant plastic deformation. Rankine's theory aligns well with this failure mode, making it the most suitable theory for brittle materials. 2. **Ductile Materials**: Ductile materials (like mild steel) usually fail due to shear (sliding of planes). Therefore, theories based on shear stress, such as the Maximum Shear Stress Theory (Tresca) or the Maximum Distortion Energy Theory (von Mises), are used for ductile materials. 3. **Elastic Material**: While the theory is applied within the elastic limit, 'elastic' is a general property of both brittle and ductile materials; it is not the specific category of material for which this failure theory is uniquely applicable. Therefore, the Maximum Principal Stress Theory is specifically applicable to brittle materials.