Friction and Free Body Diagram MCQs

Friction and Free Body Diagram MCQs – Class 11 Physics

Class: 11
Subject: Physics
Section: Laws of Motion
Topic: Friction and Free Body Diagram MCQs
Board: CBSE Board Examination (NCERT Based)

Instructions: These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 11 board examination standards.

Q1. Friction always acts:

A) Along motion
B) Opposite to relative motion
C) Vertically upward
D) Along normal reaction

Answer: B) Opposite to relative motion

Friction opposes the tendency of relative motion between two surfaces in contact.

Q2. Unit of coefficient of friction is:

A) Newton
B) kg
C) Dimensionless
D) Joule

Answer: C) Dimensionless

It is a ratio of two forces, so it has no unit.

Q3. Limiting friction acts when body is:

A) At rest
B) About to move
C) Moving fast
D) Falling freely

Answer: B) About to move

Limiting friction is the maximum static friction before motion starts.

Q4. Kinetic friction is generally:

A) Greater than static
B) Equal to static
C) Less than static
D) Zero

Answer: C) Less than static

Once motion begins, friction reduces slightly.

Q5. Normal reaction acts:

A) Parallel to surface
B) Perpendicular to surface
C) Along motion
D) Opposite gravity

Answer: B) Perpendicular to surface

Normal force is always perpendicular to the contact surface.

Q6. Free body diagram shows:

A) Internal forces only
B) External forces only
C) Both internal & external
D) Only friction

Answer: B
FBD isolates body showing all external forces.

Q7. Weight in FBD acts:

A) Upward B) Downward C) Horizontal D) Inclined

Answer: B

Q8. Friction direction on moving block:

A) Same as motion B) Opposite motion C) Vertical D) Zero

Answer: B

Q9. On incline, normal reaction equals:

A) mg B) mg cosθ C) mg sinθ D) Zero

Answer: B

Q10. Component causing sliding on incline:

A) mg cosθ B) mg sinθ C) Normal D) Friction

Answer: B

Q11. Rolling friction is:

A) Maximum B) Minimum C) Equal static D) Infinite

Answer: B

Q12. Static friction varies:

A) Constant B) Up to limit C) Zero D) Infinite

Answer: B

Q13. μ =

A) F/N B) N/F C) mg/N D) F/m

Answer: A

Q14. Lubricants reduce:

A) Mass B) Friction C) Gravity D) Force

Answer: B

Q15. Rough surface → friction:

A) Less B) More C) Zero D) Same

Answer: B

Q16. FBD first step:

A) Draw forces B) Isolate body C) Add mass D) Add velocity

Answer: B

Q17. Tension acts:

A) Push B) Pull C) Vertical only D) Zero

Answer: B

Q18. Incline angle ↑ → friction needed:

A) Less B) More C) Same D) Zero

Answer: B

Q19. If N doubles, friction:

A) Halves B) Doubles C) Same D) Zero

Answer: B

Q20. Sliding block → friction type:

A) Static B) Limiting C) Kinetic D) Rolling

Answer: C

Q21. FBD arrows represent:

A) Velocity B) Forces C) Energy D) Work

Answer: B

Q22. Maximum static friction:

A) μN B) N/μ C) μ/m D) mg

Answer: A

Q23. Friction independent of:

A) Nature surface B) Normal reaction C) Area (ideal) D) Roughness

Answer: C

Q24. Walking possible due to:

A) Static friction B) Rolling C) Kinetic D) Air

Answer: A

Q25. Ice → friction:

A) High B) Low C) Infinite D) Zero always

Answer: B

Q26. FBD helps find:

A) Net force B) Energy C) Heat D) Charge

Answer: A

Q27. Angle of repose when:

A) Sliding starts B) Rest C) Falling D) Rolling

Answer: A

Q28. μ = tanθ for:

A) Projectile B) Incline limiting case C) Circular D) Free fall

Answer: B

Q29. More mass → friction:

A) Less B) More C) Same D) Zero

Answer: B

Q30. Smooth surface → friction:

A) High B) Low C) Infinite D) Constant

Answer: B

Friction and Free Body Diagram MCQs

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