PART–4 (x) : IIT / JEE PYQs – Final Wrap-Up (With Tricks, Tips & Examiner Patterns)

This final section consolidates high-value PYQs with time-saving tricks, decision rules, and examiner pattern insights. Use this as a last-phase booster.

PYQ–46 (JEE Advanced)

Question: A force acts perpendicular to the velocity of a particle. What changes?

Core Logic: Work done depends on force component along velocity.

Solution: Perpendicular force does zero work ⇒ KE constant ⇒ speed constant, direction changes.

TRICK: ⟂ force ⇒ no work ⇒ speed unchanged.

PYQ–47 (JEE Main)

Question: A body has zero velocity but non-zero acceleration. Identify the situation.

Solution: Highest point of vertical motion (v=0, a=g).

TRICK: v=0 ≠ a=0 (check forces).

PYQ–48 (JEE Advanced)

Question: A block doesn’t move though a force is applied. What balances it?

Solution: Static friction self-adjusts to equal applied force (up to μ_sN).

TIP: Static friction ≠ μmg always.

PYQ–49 (JEE Advanced)

Question: Acceleration decreases while speed increases. Explain.

Solution: Net force decreases (e.g., rising friction), still positive ⇒ speed increases but at decreasing rate.

TRICK: Look at net force trend, not velocity.

PYQ–50 (JEE Main)

Question: Two equal & opposite forces act on a body. Can it accelerate?

Solution: If on same body ⇒ net force zero ⇒ no acceleration.

TRAP: Don’t confuse with action–reaction (different bodies).

EXAMINER PATTERNS (READ CAREFULLY)

They test force vs velocity confusion.
They hide answers in extreme cases (free fall, v=0, steady speed).
They prefer directional reasoning over heavy math.
They mix friction + FBD to trigger sign mistakes.

MASTER SHORTCUTS (SAVE THIS LIST)

Short time force ⇒ use impulse.
Constant speed ⇒ check if direction changes (centripetal!).
v constant ⇒ a=0 ⇒ ΣF=0.
v changing ⇒ a≠0 ⇒ ΣF≠0.
Static friction adjusts automatically (≤ μ_sN).
Always draw FBD first; equations later.

ONE-MINUTE DECISION FLOW (EXAM USE)

Is acceleration present?
Which direction?
Which forces act?
Balance or F=ma?
Check extreme cases.

PART–4 (x) COMPLETED.
PYQs + Tricks + Patterns covered: 50+
This chapter is now fully optimized for IIT–JEE.

📚 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.

🧠 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

MIND GROW Magazine