# Engineering Mechanics Interview Questions and Answers

## Q: What is Engineering Mechanics?

Engineering Mechanics is a branch of science that deals with the study of the behavior of objects under the action of external forces. It involves the application of principles from physics and mathematics to analyze, design, and solve problems related to the motion and deformation of solids and fluids.

## Q: What are the two main branches of Engineering Mechanics?

The two main branches of Engineering Mechanics are Statics and Dynamics.

## Q: What is Statics?

Statics is the branch of Engineering Mechanics that deals with the study of objects at rest or in equilibrium under the action of external forces. It involves the analysis of forces, moments, and couples acting on a body and the determination of the resultant forces and moments.

## Q: What is Dynamics?

Dynamics is the branch of Engineering Mechanics that deals with the study of objects in motion under the action of external forces. It involves the analysis of the kinematics and kinetics of particles, rigid bodies, and fluids.

## Q: What is the difference between Kinematics and Kinetics?

Kinematics is the branch of mechanics that deals with the study of motion without considering the forces that cause the motion, while kinetics is the branch of mechanics that deals with the study of motion in relation to the forces that cause it.

## Q: What is Newton's First Law of Motion?

Newton's First Law of Motion, also known as the Law of Inertia, states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity along a straight line unless acted upon by an external force.

## Q: What is Newton's Second Law of Motion?

Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

## Q: What is Newton's Third Law of Motion?

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction.

## Q: What is the difference between a scalar and a vector quantity?

A scalar quantity is a physical quantity that has only magnitude, such as mass, length, or temperature. A vector quantity is a physical quantity that has both magnitude and direction, such as force, velocity, or acceleration.

## Q: What is a moment of a force?

The moment of a force, also known as torque, is the product of the force and the perpendicular distance from the point of application of the force to the axis of rotation.

## Q: What is the difference between a concentrated load and a distributed load?

A concentrated load is a single force acting on a small area of a body, while a distributed load is a force that is distributed over a larger area or along a line.

## Q: What is the difference between stress and strain?

Stress is the internal resistance of a body to external forces per unit area, while strain is the deformation of a body due to stress.

## Q: What is the difference between tensile stress and compressive stress?

Tensile stress is the stress that tends to stretch or pull apart a material, while compressive stress is the stress that tends to compress or push together a material.

## Q: What is the difference between elastic and plastic deformation?

Elastic deformation is the temporary deformation of a material that is reversible when the applied stress is removed, while plastic deformation is the permanent deformation of a material that is irreversible.

## Q: What is the difference between a shear force and a bending moment?

A shear force is a force that acts perpendicular to the axis of a body, causing it to slide or shear, while a bending moment is a moment that causes a body to bend or deform.

## Q: What is the principle of virtual work?

The principle of virtual work states that for a body in equilibrium, the work done by the external forces is equal to the work done by the internal forces.

## Q: What is the difference between a statically determinate and indeterminate system?

A statically determinate system is one in which the internal forces can be calculated using the equations of equilibrium, while a statically indeterminate system is one in which the internal forces cannot be calculated using the equations of equilibrium alone.

## Q: What is the difference between a free body diagram and a shear and moment diagram?

A free body diagram shows all the external forces acting on a body and the forces that the body exerts on its supports, while a shear and moment diagram shows the shear force and bending moment at each point along a beam.

## Q: What is the difference between a truss and a beam?

A truss is a structure made up of connected triangles that is used to support a load, while a beam is a structural element that is designed to resist bending and shear forces.

## Q: What is the difference between a simple and a compound machine?

A simple machine is a device that can change the magnitude or direction of a force, while a compound machine is a combination of two or more simple machines.

## Q: What is the difference between a fluid and a solid?

A fluid is a substance that can flow and take the shape of its container, while a solid is a substance that has a fixed shape and volume.

## Q: What is Bernoulli's equation?

Bernoulli's equation states that the pressure of a fluid decreases as the velocity of the fluid increases.

## Q: What is the difference between laminar and turbulent flow?

Laminar flow is smooth and orderly, with the fluid moving in layers, while turbulent flow is chaotic and irregular, with the fluid moving in eddies and swirls.

## Q: What is the difference between a centrifugal pump and a positive displacement pump?

A centrifugal pump is a type of pump that uses a rotating impeller to move fluid, while a positive displacement pump is a type of pump that uses a fixed cavity to trap fluid and then expel it.

## Q: What is the difference between a heat engine and a heat pump?

A heat engine is a device that converts thermal energy into mechanical energy, while a heat pump is a device that uses mechanical energy to move thermal energy from a cooler to a warmer location.

## Q: What is the difference between conduction, convection, and radiation?

Conduction is the transfer of heat through a material, while convection is the transfer of heat by the movement of a fluid, and radiation is the transfer of heat through electromagnetic waves.

## Q: What is Hooke's law?

Hooke's law states that the force exerted by a spring is proportional to its displacement from its equilibrium position.

## Q: What is the difference between stress and strain?

Stress is the internal force per unit area that a material experiences when subjected to an external force, while strain is the deformation or change in shape that a material experiences when subjected to stress.

## Q: What is the difference between compression and tension?

Compression is the stress that occurs when a material is squeezed or pressed, while tension is the stress that occurs when a material is pulled or stretched.

## Q: What is the difference between a static and dynamic load?

A static load is a load that is applied to a structure or material and does not change over time, while a dynamic load is a load that changes over time.

## Q: What is the difference between a cantilever and a simply supported beam?

A cantilever is a beam that is supported at one end and free at the other, while a simply supported beam is a beam that is supported at both ends.

## Q: What is the difference between an ideal and a real fluid?

An ideal fluid is a hypothetical fluid that has no viscosity, while a real fluid has viscosity, which is the resistance of a fluid to flow.

## Q: What is the difference between a thermodynamic system and a control volume?

A thermodynamic system is a fixed amount of matter and energy that is studied in thermodynamics, while a control volume is an arbitrary region in space that is used to analyze the flow of matter and energy.

## Q: What is the difference between stress and strain?

Stress is the internal force per unit area within a material that develops in response to an external load, while strain is the deformation or change in shape that occurs in a material as a result of stress.

## Q: What is Hooke's Law?

Hooke's Law states that the deformation of a solid material is directly proportional to the force applied to it, within the material's elastic limit.

## Q: What is the difference between a rigid body and a deformable body?

A rigid body is a body that maintains its shape and size under the influence of external forces, while a deformable body is a body that changes its shape and size under the influence of external forces.

## Q: What is the difference between a closed system and an open system?

A closed system is a system that does not exchange matter with its surroundings, while an open system is a system that can exchange matter and energy with its surroundings.

## Q: What is the difference between work and power?

Work is the energy transferred to or from a system by a force acting on it over a distance, while power is the rate at which work is done or energy is transferred.

## Q: What is the difference between static and dynamic friction?

Static friction is the frictional force that resists the initial motion of a stationary object, while dynamic friction is the frictional force that resists the motion of an object that is already in motion.

## Q: What is the difference between torque and moment of inertia?

Torque is the force that causes rotational motion, while moment of inertia is a measure of an object's resistance to rotational motion.

## Q: What is the difference between elastic and inelastic collisions?

In an elastic collision, the total kinetic energy of the system is conserved, while in an inelastic collision, some or all of the kinetic energy is converted to other forms of energy, such as heat or sound.

## Q: What is the difference between impulse and momentum?

Impulse is the change in momentum of an object due to a force acting on it for a certain period of time, while momentum is the product of an object's mass and velocity.

## Q: What is the difference between centripetal force and centrifugal force?

Centripetal force is the force that keeps an object moving in a circular path, while centrifugal force is the apparent outward force that seems to act on an object moving in a circular path.

## Q: What is the difference between a stress-strain curve and a load-deformation curve?

A stress-strain curve plots the stress (force per unit area) applied to a material against the resulting strain (deformation per unit length) it undergoes, while a load-deformation curve plots the load (force) applied to a structure against the resulting deformation it undergoes.

## Q: What is the difference between a beam and a truss?

A beam is a structural element designed to support loads by resisting bending and shear forces, while a truss is a structure made of interconnected triangles designed to support loads by resisting tension and compression forces.

## Q: What is the difference between static and dynamic loads?

Static loads are loads that are applied slowly and remain constant over time, while dynamic loads are loads that change in magnitude or direction over time.

## Q: What is the difference between a distributed and a concentrated load?

A distributed load is a load that is spread out over a length or area, while a concentrated load is a load that is applied at a single point or over a very small area.

## Q: What is the difference between a simply supported beam and a cantilever beam?

A simply supported beam is a beam that is supported at two points, while a cantilever beam is a beam that is fixed at one end and free at the other.

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