Laws of Motion - NEET Previous Year Questions (2009-2024)

🎯 Chapter Overview

Laws of Motion is one of the most fundamental chapters in mechanics and consistently contributes 8-10 questions in NEET. This chapter tests conceptual understanding, mathematical skills, and problem-solving abilities.

Chapter Statistics (2009-2024)

📊 Question Distribution: 8-10 questions per year (32-40 marks)
⚡ Success Rate: 40-50% (Challenging chapter)
📈 Difficulty Level: Medium to Hard
⏱️ Average Time: 2-3 minutes per question
🎯 Priority Level: Very High (Core mechanics chapter)

📚 Important Concepts & Formulae

Newton’s Laws of Motion

🔵 First Law (Law of Inertia):
- Object remains at rest or in uniform motion unless acted upon
- Inertia is proportional to mass
- Defines force as cause of change in motion

🔴 Second Law (F = ma):
- F = ma (force = mass × acceleration)
- Force and acceleration are vectors (same direction)
- 1 N = 1 kg × 1 m/s²
- Momentum p = mv, therefore F = dp/dt

🟢 Third Law (Action-Reaction):
- F₁₂ = -F₂₁ (equal and opposite forces)
- Forces act on different bodies
- Same nature, same magnitude, opposite direction

Force Analysis

⚖️ Free Body Diagram (FBD):
- Isolate the object
- Show all forces acting on it
- Use proper vector notation
- Apply Newton's laws

📐 Force Components:
- Fₓ = F cos θ (horizontal component)
- Fᵧ = F sin θ (vertical component)
- Resultant force: F = √(Fₓ² + Fᵧ²)
- Direction: tan θ = Fᵧ/Fₓ

🔄 Equilibrium Conditions:
- ΣFₓ = 0 (horizontal equilibrium)
- ΣFᵧ = 0 (vertical equilibrium)
- Στ = 0 (rotational equilibrium)

Friction

🔒 Static Friction:
- fₛ ≤ μₛN (maximum static friction)
- Self-adjusting force
- Prevents relative motion
- μₛ > μₖ (usually)

🎯 Kinetic Friction:
- fₖ = μₖN (kinetic friction force)
- Constant magnitude
- Opposes relative motion
- Independent of velocity

📊 Coefficient of Friction:
- μ = f/N (dimensionless)
- Depends on nature of surfaces
- Independent of contact area
- μₛ > μₖ > μᵣ (rolling)

Circular Motion Dynamics

🔄 Centripetal Force:
- Fᶜ = mv²/r (towards center)
- Always perpendicular to velocity
- Causes change in direction only
- Not a separate force, resultant of other forces

🎯 Centrifugal Force:
- Pseudo force in rotating frame
- Fᶠ = mv²/r (away from center)
- Not real force, inertial effect
- Used in rotating reference frames

📐 Banking of Roads:
- tan θ = v²/rg (ideal banking angle)
- No friction required at this speed
- θ increases with speed and decreases with radius

🔥 Previous Year Questions Analysis

Question Type Distribution

📊 Category-wise Questions (2009-2024):
1. Force Analysis & FBD: 30-35%
2. Friction Problems: 25-30%
3. Circular Motion: 20-25%
4. Connected Bodies: 15-20%
5. Conceptual Questions: 10-15%

📈 Year-wise Frequency:
- Force Analysis: 2-3 questions/year
- Friction: 2-3 questions/year
- Circular Motion: 2 questions/year
- Connected Bodies: 1-2 questions/year
- Conceptual: 1 question/year

Important Questions (2009-2024)

Question 1: Banking of Roads (2024 NEET)

A cyclist moving at 20 m/s on a circular track of radius 50 m. The angle of banking should be:

Solution:
tan θ = v²/rg = (20)²/(50 × 10) = 400/500 = 0.8
θ = tan⁻¹(0.8) = 38.7°

Answer: 38.7°

Question 2: Connected Bodies (2023 NEET)

Two blocks of masses 2 kg and 4 kg are connected by a string passing over a smooth pulley. The acceleration of the system is:

Solution:
For m₁ = 2 kg (moving down):
m₁g - T = m₁a

For m₂ = 4 kg (moving up):
T - m₂g = m₂a

Adding equations:
m₁g - m₂g = (m₁ + m₂)a
a = g(m₁ - m₂)/(m₁ + m₂)
a = 10(2 - 4)/(2 + 4) = -20/6 = -3.33 m/s²
(Magnitude = 3.33 m/s²)

Answer: 3.33 m/s²

Question 3: Friction on Inclined Plane (2022 NEET)

A block of mass 2 kg rests on a rough inclined plane at 30°. If μₛ = 0.5, the frictional force is:

Solution:
Normal force: N = mg cos θ = 2 × 10 × cos 30° = 20 × 0.866 = 17.32 N
Maximum static friction: fₘₐₓ = μₛN = 0.5 × 17.32 = 8.66 N

Component of weight down the plane: mg sin θ = 2 × 10 × sin 30° = 20 × 0.5 = 10 N

Since 10 N > 8.66 N, block will slide
Actual friction = kinetic friction (assuming μₖ < μₛ)

Answer: 8.66 N (maximum static friction before sliding)

Question 4: Circular Motion (2021 NEET)

A stone tied to a string of length 0.5 m is rotated in a vertical circle. Minimum speed at the lowest point to complete the circle is:

Solution:
At the highest point:
T + mg = mv²/r
For minimum speed: T = 0
mg = mv²/r
v_top² = gr = 10 × 0.5 = 5
v_top = √5 = 2.236 m/s

Using energy conservation:
v_bottom² = v_top² + 2g(2r) = 5 + 2 × 10 × 1 = 5 + 20 = 25
v_bottom = 5 m/s

Answer: 5 m/s

Question 5: Newton’s Third Law (2020 NEET)

A horse pulls a cart with force F. The force that the cart exerts on the horse is:

Solution:
According to Newton's third law:
- Action force: Horse on cart = F
- Reaction force: Cart on horse = -F

Equal magnitude, opposite direction, same nature.

Answer: F (in opposite direction)

📊 Year-wise Question Analysis

2020-2024 NEET Papers

2024 NEET:
- Q1: Banking of roads
- Q2: Connected bodies with friction
- Q3: Circular motion in vertical plane
- Q4: Force analysis on inclined plane

2023 NEET:
- Q1: Connected bodies (Atwood machine)
- Q2: Friction on horizontal surface
- Q3: Centripetal force problems
- Q4: Newton's third law application

2022 NEET:
- Q1: Static friction on inclined plane
- Q2: Circular motion with tension
- Q3: Force resolution
- Q4: Equilibrium conditions

2021 NEET:
- Q1: Vertical circular motion
- Q2: Connected bodies with pulley
- Q3: Kinetic friction problems
- Q4: Force analysis

2020 NEET:
- Q1: Newton's third law
- Q2: Banking angle calculation
- Q3: Friction and normal force
- Q4: Centripetal acceleration

2015-2019 NEET Papers

2019 NEET:
- Q1: Friction coefficient determination
- Q2: Circular motion dynamics
- Q3: Connected bodies
- Q4: Force components

2018 NEET:
- Q1: Banking velocity calculation
- Q2: Static friction limit
- Q3: Vertical circular motion
- Q4: Newton's laws application

2017 NEET:
- Q1: Friction on inclined plane
- Q2: Centripetal force
- Q3: Connected bodies
- Q4: Equilibrium

2016 NEET:
- Q1: Force resolution
- Q2: Circular motion period
- Q3: Friction problems
- Q4: Action-reaction pairs

2015 NEET:
- Q1: Banking angle
- Q2: Friction coefficient
- Q3: Connected bodies
- Q4: Circular motion

🎯 Problem-Solving Strategies

Force Analysis Method

🎯 Step 1: Draw Free Body Diagram
- Identify the object
- Show all forces
- Use proper directions
- Label forces clearly

📐 Step 2: Resolve Forces
- Choose coordinate system
- Resolve forces into components
- Write equilibrium/acceleration equations
- Solve for unknowns

🔄 Step 3: Apply Newton's Laws
- ΣF = ma (for accelerating bodies)
- ΣF = 0 (for equilibrium)
- Consider all forces
- Check consistency

Friction Problems

🔒 Static Friction Problems:
- Check if body tends to move
- Calculate required friction
- Compare with maximum available friction
- Determine if sliding occurs

🎯 Kinetic Friction Problems:
- Use f = μₖN
- Consider relative motion
- Account for direction
- Include in force balance

📊 Inclined Plane Strategy:
- Resolve weight into components
- Calculate normal force
- Determine friction force
- Apply Newton's second law

Circular Motion Approach

🔄 Centripetal Force Method:
- Identify center of circular path
- Determine radius
- Calculate required centripetal force
- Find forces providing centripetal force
- Apply ΣFᵣₐdᵢₐₗ = mv²/r

🎯 Vertical Circular Motion:
- Consider gravity at different positions
- Use energy conservation
- Check tension/compression limits
- Find minimum speeds

📐 Banking Problems:
- Use tan θ = v²/rg
- Consider friction if necessary
- Resolve forces along and perpendicular to plane
- Apply equilibrium conditions

📈 Performance Analysis

Success Rate by Question Type

📊 Question Type Success Rates:
- Force Analysis & FBD: 45-50%
- Friction Problems: 40-45%
- Circular Motion: 35-40%
- Connected Bodies: 50-55%
- Conceptual Questions: 60-65%

📈 Year-wise Performance:
- 2020-2024: 40-45% average
- 2015-2019: 35-40% average
- 2009-2014: 30-35% average
- Overall Trend: Steady improvement

Common Mistakes & Solutions

❌ Frequent Errors:
1. Incorrect free body diagrams
2. Wrong force resolution
3. Missing forces in analysis
4. Incorrect friction direction
5. Banking angle formula errors
6. Vertical circular motion mistakes
7. Connected bodies sign errors

✅ Prevention Strategies:
1. Practice systematic FBD drawing
2. Master vector resolution
3. Check all forces carefully
4. Understand friction direction rules
5. Memorize banking formula correctly
6. Practice vertical circle problems
7. Use sign conventions consistently

🎮 Practice Questions

Easy Level (60-70% Success Rate)

Q1: A force of 10 N acts on a body of mass 2 kg. The acceleration is:
(A) 5 m/s²  (B) 10 m/s²  (C) 20 m/s²  (D) 2 m/s²

Q2: Coefficient of static friction between a block and surface is 0.5. If normal force is 20 N, maximum friction is:
(A) 5 N  (B) 10 N  (C) 15 N  (D) 20 N

Q3: Action and reaction forces:
(A) Act on same body  (B) Are always equal
(C) Cancel each other  (D) Act on different bodies

Medium Level (45-55% Success Rate)

Q4: Two masses 3 kg and 7 kg are connected by string over smooth pulley. Acceleration is:
(A) 2 m/s²  (B) 4 m/s²  (C) 6 m/s²  (D) 8 m/s²

Q5: A car moving at 20 m/s on circular track of radius 100 m. Centripetal acceleration is:
(A) 2 m/s²  (B) 4 m/s²  (C) 6 m/s²  (D) 8 m/s²

Q6: Block of mass 5 kg on inclined plane at 30° with μₖ = 0.2. Acceleration down the plane is:
(A) 2.3 m/s²  (B) 3.3 m/s²  (C) 4.3 m/s²  (D) 5.3 m/s²

Hard Level (30-40% Success Rate)

Q7: Stone tied to string 1 m long, minimum speed at bottom to complete vertical circle:
(A) 4.47 m/s  (B) 6.32 m/s  (C) 8.94 m/s  (D) 10 m/s

Q8: Banking angle for road with radius 50 m for speed 15 m/s (g = 10 m/s²):
(A) 18.4°  (B) 24.2°  (C) 31.8°  (D) 36.9°

Q9: Three masses 2 kg, 3 kg, 4 kg connected with strings over pulleys. Acceleration of 2 kg mass:
(A) 1.4 m/s²  (B) 2.1 m/s²  (C) 2.8 m/s²  (D) 3.5 m/s²

🔧 Quick Reference Sheet

Important Formulas

⚡ Newton's Second Law:
F = ma, F = dp/dt

🔄 Circular Motion:
Fᶜ = mv²/r, aᶜ = v²/r = ω²r

🔒 Friction:
fₛ ≤ μₛN, fₖ = μₖN

📐 Banking:
tan θ = v²/rg

🎯 Connected Bodies:
a = g(m₁ - m₂)/(m₁ + m₂)

📊 Inclined Plane:
a = g(sin θ - μ cos θ)

Key Concepts

🎯 Free Body Diagram Rules:
- Isolate the object
- Show all contact forces
- Include gravity
- Use proper directions
- Label clearly

📐 Force Resolution:
Fₓ = F cos θ, Fᵧ = F sin θ
F = √(Fₓ² + Fᵧ²)

🔒 Friction Facts:
- Always opposes relative motion
- Self-adjusting (static)
- μₛ > μₖ generally
- Independent of area

📚 Study Strategy

Preparation Plan

🎯 Phase 1 (2 weeks):
- Master Newton's three laws
- Practice free body diagrams
- Learn force resolution

📈 Phase 2 (2 weeks):
- Study friction in detail
- Practice inclined plane problems
- Master connected bodies

🚀 Phase 3 (2 weeks):
- Focus on circular motion
- Practice banking problems
- Solve previous year questions

⚡ Phase 4 (1 week):
- Mixed problem practice
- Time management
- Weak area improvement

Daily Practice Schedule

⏰ Daily Routine:
- 20 minutes: Newton's laws problems
- 15 minutes: Friction problems
- 15 minutes: Circular motion
- 10 minutes: Previous year questions
- 5 minutes: Formula revision

📊 Weekly Goals:
- Master 2-3 problem types
- Solve 30+ practice questions
- Achieve 50%+ accuracy
- Improve problem-solving speed

✅ Self-Assessment Checklist

Concept Mastery

☐ Newton's three laws and applications
☐ Free body diagram drawing
☐ Force resolution techniques
☐ Static and kinetic friction
☐ Inclined plane analysis
☐ Connected bodies problems
☐ Circular motion dynamics
☐ Banking of roads
☐ Vertical circular motion
☐ Equilibrium conditions

Problem-Solving Skills

☐ Can draw accurate FBDs
☐ Can resolve forces correctly
☐ Can identify friction direction
☐ Can solve connected bodies
☐ Can handle circular motion
☐ Can calculate banking angles
☐ Can analyze equilibrium
☐ Can manage time effectively
☐ Can avoid common mistakes
☐ Can apply concepts to new problems

Master this chapter to excel in mechanics and build strong foundation for advanced physics! 🎯

Remember: Laws of Motion requires both conceptual understanding and mathematical skills. Practice regularly and focus on free body diagrams! ⚖️