PART–4 : IIT / JEE Previous Year Questions (PYQs)
This section contains authentic previous IIT / JEE-type questions from different years. Each question is followed by:
- Correct method of approach
- Step-by-step solution
- Examiner’s intention
- Common student mistakes
PYQ–1 (IIT–JEE)
Question:
A block of mass m rests on a smooth horizontal surface. A constant horizontal force F is applied. Find the acceleration of the block.
Method Selection:
Since a force produces acceleration, Newton’s Second Law (F = ma) must be used. Energy or momentum methods are not applicable.
Solution:
Net force acting on the block = F
Using F = ma,
a = F / m
Examiner’s Intention:
To check whether the student understands the direct relation between force and acceleration.
Common Mistake:
Students unnecessarily apply equations of motion.
PYQ–2 (IIT–JEE)
Question:
A block of mass 2 kg is placed on a rough horizontal surface. Coefficient of friction is 0.2. Find the minimum horizontal force required to just start the motion. (Take g = 10 m/s2)
Method Selection:
This is a force balance problem. Use Newton’s laws with friction.
Solution:
Normal reaction, N = mg = 2 × 10 = 20 N
Maximum friction, f = μN = 0.2 × 20 = 4 N
Minimum force required = friction force = 4 N
Examiner’s Intention:
To test understanding of limiting friction and equilibrium.
Common Mistake:
Taking friction as μmg without checking motion condition.
PYQ–3 (IIT–JEE)
Question:
Two blocks of masses m and 2m are connected by a light string and pulled by a force F on a smooth surface. Find the acceleration of the system.
Method Selection:
Treat both blocks as a single system. Use Newton’s Second Law.
Solution:
Total mass = m + 2m = 3m
Net force = F
Using F = ma,
a = F / 3m
Examiner’s Intention:
To test system approach instead of individual force equations.
Common Mistake:
Writing separate equations unnecessarily and getting confused.
PYQ–4 (IIT–JEE)
Question:
A lift is moving upward with acceleration a. Find the apparent weight of a person of mass m inside the lift.
Method Selection:
Use Free Body Diagram and Newton’s Second Law.
Solution:
Forces acting: Normal reaction N upward, weight mg downward.
Applying F = ma upward,
N − mg = ma
N = m(g + a)
Examiner’s Intention:
To test understanding of non-inertial motion.
Common Mistake:
Students write N = mg even when acceleration is present.
PYQ–5 (IIT–JEE)
Question:
A body of mass m is thrown vertically upward. Which force acts on it at the highest point?
Method Selection:
Conceptual question based on Newton’s laws.
Solution:
At the highest point, velocity is zero but acceleration is not zero.
Only gravitational force acts downward.
Force = mg (downward)
Examiner’s Intention:
To check the difference between velocity and acceleration.
Common Mistake:
Students say force is zero because velocity is zero.
Important Competitive Tips
- If acceleration exists, force must exist.
- Always draw Free Body Diagram first.
- Choose system approach wherever possible.
- Do not confuse velocity with acceleration.
PART–4 (PYQs) – Section–1 Completed.
More PYQs will follow to cover 30+ years of IIT/JEE papers.
📚 Physics Thinking Library – How IIT Toppers Think
Welcome to the Physics Thinking Library by Mind Grow Magazine. This library is specially designed for IIT–JEE & Intermediate students to understand how toppers think, decide, and solve Physics problems.
🎯 What You Will Learn From This Library
- How IIT toppers approach Physics questions
- Decision-making during problem solving
- Common traps & how to avoid them
- Exam-hall mindset and logic flow
- Step-by-step thinking framework
📘 Complete Series: How IIT Toppers Think (Part 1–25)
Click on any part below to start learning. It is recommended to read in order.
- Part 1 – Introduction to Topper Thinking
- Part 2 – Understanding the Problem Statement
- Part 3 – Visualization & Physical Sense
- Part 4 – Role of Acceleration & Forces
- Part 5 – Free Body Diagram Thinking
- Part 6 – Method Selection Strategy
- Part 7 – Avoiding Formula Traps
- Part 8 – System Approach Mindset
- Part 9 – Friction & Constraint Thinking
- Part 10 – Time vs Accuracy Balance
- Part 11 – Common Thinking Mistakes
- Part 12 – Decision Flow in Tough Problems
- Part 13 – Eliminating Wrong Options
- Part 14 – Handling Multi-Concept Questions
- Part 15 – Pressure Handling in Exam Hall
- Part 16 – Speed Building Without Guessing
- Part 17 – Extreme Case Thinking
- Part 18 – Logical Shortcuts vs Blind Tricks
- Part 19 – Advanced Reasoning Techniques
- Part 20 – Rank-Deciding Thought Patterns
- Part 21 – Physics Intuition Development
- Part 22 – Eliminating Panic in Tough Questions
- Part 23 – Last-Minute Thinking Strategy
- Part 24 – Mistake-Proof Problem Solving
- Part 25 – Final Topper Framework
🧠 How to Use This Library Effectively
- Read 1–2 parts daily
- Apply thinking to real Physics problems
- Revisit library before exams
- Use as a mindset guide, not memorization
This library is a long-term asset for serious Physics learners.
© Mind Grow Magazine
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