Engineering Mechanics Important Questions for JNTU R20 Students (Unit-Wise & Exam-Oriented)
Introduction
Engineering Mechanics is one of the most important foundation subjects in Mechanical Engineering. It builds the base for advanced subjects like Strength of Materials, Theory of Machines, and Machine Design.
If you’re studying under JNTU R20 Regulation (JNTUK / JNTUA / JNTUH), this post provides a complete, unit-wise list of important questions and numerical problem topics — perfect for exam preparation and quick revision.
UNIT – I: BASICS & FORCE SYSTEMS
Conceptual Questions:
Define force, resultant, and equilibrium.
Explain different types of forces with examples.
What is a free body diagram? Why is it important?
Differentiate between scalar and vector quantities.
State and explain the law of parallelogram of forces.
Explain Lami’s theorem with an example.
What are the conditions for equilibrium of a system of forces?
Explain coplanar concurrent and non-concurrent force systems.
Write short notes on Bow’s notation.
Explain moment of a force and Varignon’s theorem.
Numerical Topics:
Resultant of concurrent and non-concurrent forces.
Application of Lami’s theorem.
Equilibrium of coplanar forces using graphical and analytical methods.
Finding magnitude and direction of resultant using components.
UNIT – II: EQUILIBRIUM OF RIGID BODIES
Conceptual Questions:
Define rigid body and conditions of equilibrium.
Explain different types of supports and their reactions.
What is a free-body diagram? Explain its importance in analysis.
Explain the equations of equilibrium for a planar system.
Discuss types of beams and loading conditions.
Numerical Topics:
Finding reactions for simply supported and overhanging beams.
Problems on equilibrium of ladders, beams, and trusses.
Determining unknown forces using ∑Fx = 0, ∑Fy = 0, ∑M = 0.
Calculation of support reactions under point load and UDL.
UNIT – III: CENTROID & MOMENT OF INERTIA
Conceptual Questions:
Define centroid and center of gravity.
Distinguish between centroid and center of gravity.
Explain the method of locating the centroid for composite areas.
State and explain the parallel and perpendicular axis theorems.
Define mass moment of inertia and its significance.
Explain the difference between area and mass moment of inertia.
Numerical Topics:
Centroid of simple and composite sections (T-section, I-section, L-section, etc.).
Moment of inertia of rectangular, circular, and composite sections.
Moment of inertia using theorems (parallel axis and perpendicular axis).
Calculation of radius of gyration for plane areas.
UNIT – IV: FRICTION
Conceptual Questions:
Define friction and state laws of dry friction.
Explain limiting friction, angle of friction, and coefficient of friction.
What are the differences between static and kinetic friction?
Explain the concept of rolling resistance.
What are the advantages and disadvantages of friction?
Numerical Topics:
Problems on motion of blocks on inclined planes.
Calculation of minimum force required to move a body.
Ladder friction and wedge friction problems.
Screw jack and belt friction problems.
UNIT – V: KINEMATICS & KINETICS OF PARTICLES
Conceptual Questions:
Define displacement, velocity, and acceleration.
Explain rectilinear and curvilinear motion.
Define and explain projectile motion.
State and derive the work-energy principle.
Explain impulse and momentum with examples.
Define D’Alembert’s principle and its applications.
Differentiate between kinetics and kinematics.
Numerical Topics:
Equations of motion under uniform and variable acceleration.
Projectile motion problems.
Work-energy theorem and power calculations.
Impulse and momentum principle problems.
Collision and impact of bodies (coefficient of restitution).
UNIT – VI: PLANE MOTION OF RIGID BODIES
Conceptual Questions:
Define angular velocity and angular acceleration.
Explain instantaneous center of rotation.
What is general plane motion? Give examples.
Discuss work-energy equation for rigid bodies.
Explain the principle of conservation of energy for rotation.
Numerical Topics:
Rotation about a fixed axis.
Relation between linear and angular velocity.
Plane motion combining translation and rotation.
Problems on instantaneous center of rotation.
Work-energy and impulse-momentum for rotating bodies.
📘 Extra Practice Topics (Frequently Asked in JNTU Exams)
Resultant of system of forces acting on a body.
Reactions of simply supported beams under different loading.
Centroid and M.I. for composite lamina.
Ladder and wedge friction numericals.
Projectile motion under different angles.
Rotation of rigid bodies and energy equations.
🎯 Final Exam Tips
Focus more on numerical problem-solving from R.K. Bansal and S.S. Bhavikatti books.
Revise centroid, friction, and projectile topics before the exam.
For theory, read definitions, laws, and short derivations from each unit.
Practice at least 2 model papers before final exams.
🔧 Summary
Engineering Mechanics is not just about formulas — it’s about understanding how forces act and balance. With consistent practice of both conceptual and numerical questions, you can easily score above 80% in this subject.
