Answer: Stress is the internal resistance force per unit area within a material when subjected to an external force, while a strain is the measure of deformation or elongation resulting from the applied stress. In simple terms, stress is the force applied, and strain is the response of the material to that force.

Answer: The first law of thermodynamics, also known as the law of energy conservation, states that energy cannot be created or destroyed, but it can be converted from one form to another. The second law of thermodynamics states that in a closed system, the total entropy (a measure of disorder) always tends to increase over time.

Answer: The moment of inertia of an object depends on its mass distribution and its axis of rotation. The formula to calculate the moment of inertia varies depending on the shape of the object. For example, for a solid cylinder rotating about its central axis, the moment of inertia can be calculated using the formula I = (1/2) * m * r^2, where I is the moment of inertia, m is the mass of the cylinder, and r is the radius.

Answer: A four-stroke internal combustion engine operates through four distinct strokes: intake, compression, power, and exhaust. During the intake stroke, the piston moves downward, drawing in a mixture of air and fuel into the cylinder. In the compression stroke, the piston moves upward, compressing the mixture. The power stroke occurs when the spark plug ignites the compressed mixture, resulting in an explosion that drives the piston downward. Finally, during the exhaust stroke, the piston moves upward again, expelling the exhaust gases from the cylinder.

Answer: Several factors should be considered when selecting a material for an engineering application, including mechanical properties (such as strength, stiffness, and toughness), corrosion resistance, temperature resistance, cost, availability, manufacturability, and environmental impact. The specific requirements of the application, such as load-bearing capacity, operating conditions, and desired lifespan, should also be taken into account.

Answer: Gears offer several advantages in mechanical systems, such as transmitting power efficiently, providing speed and torque conversions, and enabling directional control. In addition, they are small in size, have a high power density, and can function at a number of different speeds. However, gears have a number of drawbacks, including the production of noise, the possibility of backlash, and the requirement for regular lubrication and maintenance.

Answer: Tolerance in engineering drawings refers to the allowable variation in dimensions for a manufactured component. It ensures that the component will fit and function as intended while accounting for variations that may occur during the manufacturing process. Tolerances are typically specified as upper and lower limits, ensuring that the actual dimensions fall within the specified range.

Answer: The fatigue life of a mechanical component is determined by performing fatigue testing, which involves subjecting the component to repeated cyclic loading. The testing involves applying a varying stress or strain level to simulate real-world operating conditions. The number of cycles required to cause failure is recorded, and statistical analysis is used to estimate the component’s fatigue life under specific conditions.

Answer: A hydraulic system uses fluid (typically oil) to transmit power and control motion. The system consists of a hydraulic pump that pressurizes the fluid, actuators (such as hydraulic cylinders or motors) that convert the fluid’s energy into mechanical work, valves for controlling the fluid flow, and piping or tubing to transport the fluid. Hydraulic systems find applications in various fields, such as construction equipment, aircraft control systems, and automotive braking systems.

Answer: Heat treatment processes in metallurgy include annealing, quenching, tempering, and case hardening. Annealing involves heating the metal to a high temperature and then slowly cooling it to improve its ductility and reduce internal stresses. Quenching involves rapid cooling to increase hardness, while tempering is a subsequent heating process to improve toughness and reduce brittleness. Case hardening involves adding a hard outer layer to a softer core to enhance wear resistance.

Answer: Kinematics is the study of motion, specifically the geometry and time-based properties of motion, without considering the forces causing the motion. It focuses on aspects such as position, velocity, and acceleration. Kinematics is essential in mechanical engineering as it helps analyze and design mechanisms, understand the behavior of moving components, and optimize motion control systems.

Answer: A heat exchanger is a device used to transfer heat energy between two fluids while keeping them physically separated. It is commonly used in heating, ventilation, and air conditioning (HVAC) systems, power plants, and various industrial processes. Heat exchangers work by allowing the transfer of heat from a hot fluid to a cooler fluid through thermal conduction, without the fluids mixing.

Answer: Finite Element Analysis (FEA) is a numerical method used to analyze the stress distribution and deformation of a mechanical component. The process involves discretizing the component into a mesh of smaller elements, applying appropriate boundary conditions, and solving the governing equations numerically. FEA helps predict how a component will behave under different loading conditions, aiding in design optimization and ensuring structural integrity.

Answer: When designing a gear system, some key parameters to consider include the gear ratio, module or pitch, tooth profile, face width, and material selection. The speed and torque relationship between the driving gear and the gear that it is driving is determined by the gear ratio. The module, also known as the pitch, is what determines the size of the gear teeth as well as their spacing. The effectiveness and consistency of the gear engagement are both impacted by the tooth profile. The load-carrying capacity is directly proportional to the face width. When selecting a material, it is important to take into consideration things like its cost, its wear resistance, and its strength.

Answer: The coefficient of thermal expansion (CTE) measures how a material expands or contracts with temperature changes. It quantifies the fractional change in length or volume per unit change in temperature. CTE is essential in mechanical engineering as it helps predict and compensate for thermal expansion or contraction in different materials, preventing unwanted distortions, stresses, or failures in structures and components.

Answer: There are several machining processes used in manufacturing, including turning, milling, drilling, grinding, and broaching. Turning involves rotating the workpiece while a cutting tool removes material to create cylindrical shapes. Milling uses rotating multi-point cutting tools to remove material and create complex shapes. Drilling involves creating holes in a workpiece using a rotating drill bit. Grinding uses abrasive particles to remove material and achieve high surface finish. Broaching is a process that uses a specialized tool to cut intricate shapes or profiles into a workpiece.

Answer: Ductile materials can undergo significant plastic deformation before fracture, whereas brittle materials tend to fracture with little or no plastic deformation. Materials that are ductile have a high tensile strength and are able to sustain forces of stretching as well as bending. Steel and aluminium are two examples of materials that fall into the ductile category. Cast iron and glass are two examples of brittle materials that have a low tensile strength and are prone to rapid fractures without any prior warning.

Answer: A flywheel is a rotating mechanical device used to store rotational energy. It helps stabilize and maintain the rotational motion of a system by storing excess energy during periods of high power input and releasing it during periods of low power input. Flywheels are commonly used in applications where a steady and continuous output is required, such as engines, power generation systems, and energy storage systems.

Answer: A steam turbine is a device that converts the thermal energy of pressurized steam into mechanical work. The working principle involves high-pressure steam entering the turbine, which then expands and passes through a series of turbine blades or buckets. The steam’s high velocity causes the blades to rotate, and the rotational motion is transferred to a generator or mechanical system, producing electricity or driving machinery.

Answer: In a riveted joint, two or more plates are joined together using metal rivets, which are inserted and permanently deformed to secure the plates. Riveted joints offer high strength, reliability, and the ability to disassemble if needed. Welded joints, on the other hand, are formed by melting and fusing the edges of two or more plates together using heat and pressure. Welded joints provide excellent strength and rigidity but are generally not easily disassembled.