Friction Questions for NEET 2027All 35 problems — MCQs, numericals & ReNEET 2026-style reasoning, with worked solutions

✨ Practise all 35 Friction Questions

Friction is a high-yield part of Laws of Motion. This is the complete set — real NEET PYQs plus ReNEET 2026-style reasoning, each with an instant worked solution.

1. Q1. A block of mass 4 kg is placed at rest on a rough inclined plane of inclination 30° and does not slide. The force of friction acting on the block is (g = 10 m/s²):
   
   A40 NB20 NC34.6 ND10 N
2. Q2. A block is placed on a rough plane whose inclination is increased gradually. The coefficient of static friction is μ = 0.75. The maximum angle of inclination (angle of repose) for which the block remains at rest is approximately:
   
   A30°B37°C45°D53°
3. Q3. Two inclined planes of equal length have the same inclination of 45°; one is perfectly smooth, the other rough. A body released from rest at the top takes twice as long to slide down the rough incline as down the smooth one. The coefficient of kinetic friction for the rough incline is:
   
   A0.50B0.60C0.75D0.85
4. Q4. A block slides down a rough inclined plane of inclination 37° with coefficient of kinetic friction μ = 0.5. Its acceleration down the incline is (sin37° = 0.6, cos37° = 0.8, g = 10 m/s²):
   
   A6 m/s²B4 m/s²C2 m/s²D1 m/s²
5. Q5. A block of mass 2 kg moving at 8 m/s on a rough horizontal surface (μ = 0.2) is brought to rest by friction. The distance travelled before stopping is (g = 10 m/s²):
   A8 mB16 mC12 mD20 m
6. Q6. A block rests on the floor of a truck. The coefficient of static friction between the block and the floor is 0.4. The maximum acceleration with which the truck can move so that the block does not slip is (g = 10 m/s²):
   A2 m/s²B4 m/s²C6 m/s²D8 m/s²
7. Q7. A 10 kg block rests on a rough floor with μ_s = 0.5 and μ_k = 0.4. A horizontal force of 60 N is applied. The acceleration of the block is (g = 10 m/s²):
   A0 (block stays at rest)B1 m/s²C2 m/s²D6 m/s²
8. Q8. A body of mass 5 kg rests on a rough horizontal surface (μ = 0.75). When it is on the verge of moving, the resultant of the normal reaction and the limiting friction force exerted by the surface on the body is (g = 10 m/s²):
   A50 NB37.5 NC62.5 ND100 N
9. Q9. A block rests on an inclined plane. The coefficient of static friction between the block and the plane is 1/√3. What is the maximum angle of inclination θ_max with the horizontal at which the block will just begin to slide?
   A45°B60°Ctan⁻¹(√3)D30°
10. Q10. A block of mass 5 kg rests on a horizontal surface with coefficient of static friction μₛ = 0.3. A horizontal force of 12 N is applied to the block, but it remains stationary. What is the magnitude of the frictional force acting on the block? (Take g = 10 m/s²)
    A50 NB65 NC12 ND15 N
11. Q11. A horizontal conveyor belt moves at a constant speed of 3 m/s. A small package of mass 2 kg is gently placed on the moving belt. If the coefficient of kinetic friction between the package and the belt is 0.3, how long will it take for the package to stop sliding relative to the belt? (Take g = 10 m/s²)
    A0.5 sB1.5 sC1.0 sD0.9 s
12. Q12. A block of mass 5 kg rests on a horizontal surface. The coefficient of static friction between the block and the surface is 0.4. What is the minimum horizontal force required to just start moving the block? (Take g = 10 m/s²)
    A8 NB20 NC2 ND50 N
13. Q13. A block of weight $50\text{N}$ rests on a rough horizontal floor for which ${\mu }_s=0.4$. A horizontal push of $15\text{N}$ is applied, but the block stays still. The friction force on the block is:
    A$20\text{N}$B$35\text{N}$C$5\text{N}$D$15\text{N}$
14. Q14. A block sits on a rough floor. A horizontal force $F$ on it is increased slowly from zero until the block slides and then keeps increasing. Which graph correctly shows the friction force $f$ on the block versus the applied force $F$?
    
    AGraph BBGraph ACGraph CDGraph D
15. Q15. A $5\text{kg}$ block rests on a rough floor with ${\mu }_s=0.5$ and ${\mu }_k=0.4$ ($g=10{\text{m s}}^{-2}$). The horizontal pull is slowly raised. Just after the block starts to slide (the pull equal to the maximum static friction), its acceleration is:
    A$1{\text{m s}}^{-2}$B$0{\text{m s}}^{-2}$C$0.5{\text{m s}}^{-2}$D$5{\text{m s}}^{-2}$
16. Q16. Two identical blocks rest on the same rough floor. Block $P$ is pulled by a horizontal force equal to HALF its limiting friction; block $Q$ by a force equal to TWICE its limiting friction. Which statement is correct?
    A$P$ slides while $Q$ stays at rest, by the opposite of the correct reasoningB$P$ stays still with friction equal to the applied force, while $Q$ slides with kinetic frictionCboth blocks stay completely at rest, since static friction rises to meet any applied force givenDboth blocks slide, since the applied forces are above the friction limit
17. Q17. A box lies on the floor of a truck. The truck accelerates forward at $a$ and the box does not slip. The minimum coefficient of static friction between the box and the floor must be (with $g$ the acceleration due to gravity):
    A$\frac{a}{2g}$B$ag$C$\frac{a}{g}$D$\frac{g}{a}$
18. Q18. A block slides down a rough incline of angle $37^{\circ }$ ($\sin 37^{\circ }=0.6,\cos 37^{\circ }=0.8$) for which ${\mu }_k=0.5$. Taking $g=10{\text{m s}}^{-2}$, the acceleration of the block is:
    A$6{\text{m s}}^{-2}$B$10{\text{m s}}^{-2}$C$1{\text{m s}}^{-2}$D$2{\text{m s}}^{-2}$
19. Q19. Two blocks rest on two inclines that have the SAME angle $30^{\circ }$ ($\tan 30^{\circ }\approx 0.58$). The surface under block $A$ has ${\mu }_s=0.7$ and that under block $B$ has ${\mu }_s=0.5$. Which block stays at rest?
    
    Aonly $A$Bonly $B$Cboth stay at restDboth slide
20. Q20. A block rests in equilibrium on a rough incline whose angle $20^{\circ }$ is less than the angle at which the block would begin to slide. The friction force on the block is:
    A${\mu }_{s}mg\sin 20^{\circ }$B$mg\sin 20^{\circ }$C${\mu }_{s}mg\cos 20^{\circ }$D$mg\cos 20^{\circ }$
21. Q21. A light wooden block and a heavy wooden block of the SAME material are placed on a rough plank, and the plank is slowly tilted. Which block begins to slide first?
    Athe lighter block slides first, because it is held down by less frictionBneither block slides, however far the plank is gradually tilted upCboth slide together, because the slip angle depends only on ${\mu }_s$Dthe heavier block slides first, because it presses on the plank more strongly
22. Q22. Static friction is called a 'self-adjusting' force because:
    Ait adjusts to the applied force, up to a maximum of ${\mu }_{s}N$Bit always stays fixed at the maximum value ${\mu }_{s}N$ at all timesCit keeps acting on the body even when no other force is appliedDit increases with the applied force without any upper limit at all
23. Q23. A block on a plane just begins to slide when the plane is tilted to an angle ${\theta }_{max}$. The coefficient of static friction is then:
    A$\cot {\theta }_{max}$B$\tan {\theta }_{max}$C$\sin {\theta }_{max}$D$\cos {\theta }_{max}$
24. Q24. A block is projected UP a rough incline of angle $\theta$ with kinetic friction coefficient ${\mu }_k$. While the block moves up, its deceleration (retardation) is:
    A$g\sin \theta$B${\mu }_{k}g\cos \theta$C$g(\sin \theta +{\mu }_k\cos \theta )$D$g(\sin \theta -{\mu }_k\cos \theta )$
25. Q25. A block is projected up a rough incline of angle $45^{\circ }$ with coefficient of kinetic friction ${\mu }_k=0.5$. The ratio of its retardation while moving up to its acceleration while sliding back down is:
    A$2:1$B$3:1$C$1:3$D$\sqrt{3}:1$
26. Q26. A block of mass $m$ is pulled along a horizontal floor by a rope inclined at angle $\theta$ above the horizontal with tension $T$. The normal force exerted by the floor on the block is:
    A$mg$B$mg+T\sin \theta$C$mg-T\cos \theta$D$mg-T\sin \theta$
27. Q27. A $10\text{kg}$ block on a rough horizontal floor ($\mu =0.4$) is pushed by a force of $100\text{N}$ directed at $37^{\circ }$ BELOW the horizontal ($\sin 37^{\circ }=0.6,\cos 37^{\circ }=0.8,g=10{\text{m s}}^{-2}$). The acceleration of the block is:
    A$2.0{\text{m s}}^{-2}$B$3.2{\text{m s}}^{-2}$C$1.6{\text{m s}}^{-2}$D$0.8{\text{m s}}^{-2}$
28. Q28. A block of mass $5\text{kg}$ rests on a rough horizontal floor with coefficient of static friction $\mu =0.75$. It is pulled by a rope making $37^{\circ }$ above the horizontal ($\sin 37^{\circ }=0.6,\cos 37^{\circ }=0.8,g=10{\text{m s}}^{-2}$). The tension at which the block is just about to start moving is:
    A$30\text{N}$B$37.5\text{N}$C$25\text{N}$D$45\text{N}$
29. Q29. Which of the following statements about friction is INCORRECT? (1) The coefficient of friction μ is a dimensionless quantity. (2) The force of limiting static friction is directly proportional to the normal reaction. (3) The force of kinetic friction depends strongly on the area of contact between the surfaces. (4) Friction opposes the relative motion (or its tendency) between surfaces in contact.
    AStatement (1)BStatement (2)CStatement (3)DStatement (4)
30. Q30. Which of the following statements about friction is CORRECT?
    AFriction between two surfaces always opposes the relative motion (or impending motion) between them.BStatic friction has a fixed value equal to μ_s · N at all times.CThe maximum static friction is always less than the kinetic friction.DFriction always reduces the efficiency of machines and should always be eliminated.
31. Q31. A block just begins to slide down a rough inclined plane when the inclination equals the angle of repose θ. The coefficient of friction is μ. The correct relation is:
    Aμ = sinθ, unrelated to the angle of frictionBμ = cosθ, always greater than the angle of frictionCμ = tanθ, and the angle of repose equals the angle of frictionDμ = 1/tanθ, independent of the surfaces
32. Q32. Given below are two statements: Statement I: Static friction always opposes the APPLIED tangential force (or impending motion), not the eventual motion. Statement II: Once a block has been set in motion by a small applied force, the kinetic friction force has a constant magnitude μ_k · N, independent of the applied force. In the light of the above statements, choose the correct answer from the options given below.
    ABoth Statement I and Statement II are correctBBoth Statement I and Statement II are incorrectCStatement I is correct and Statement II is incorrectDStatement I is incorrect and Statement II is correct
33. Q33. For the same pair of surfaces, the coefficients of static (μs), kinetic (μk) and rolling (μr) friction are compared. Which ordering is correct, with the right reason?
    Aμr > μk > μs, because rolling involves continuous fresh contactBμs > μk > μr, because rolling reduces the area and duration of contact/deformation so the opposing force is leastCμk > μs > μr, because kinetic friction acts only while movingDμs = μk > μr, because static and kinetic friction are always equal
34. Q34. A horizontal force F is applied to a block resting on a rough horizontal surface. The applied force is gradually increased from zero. Which of the following correctly describes the graph of the friction force f on the block versus the applied force F?
    Af stays at zero for all values of F.Bf grows linearly with F up to F = μ_s · N, then drops to μ_k · N for F > μ_s · N.Cf equals μ_s · N from the start, regardless of the value of F.Df grows quadratically with F throughout.