JEE Main PYQs on Friction: JEE Main Questions for Practice with Solutions

1.

As shown in the figure a block of mass \(10\, kg\) lying on a horizontal surface is pulled by a force \(F\)acting at an angle \(30^{\circ}\), with horizontal For \(\mu_{ s }=0.25\), the block will just start to move for the value of \(F\) : [Given g=10ms^-2]

• $20\, N$
• $35.7\, N$
• $33.3 \,N$
• $25.2\, N$

2.

A bullet of mass 0.1 kg moving horizontally with speed 400 ms^-1 hits a wooden block of mass 3.9 kg kept on a horizontal rough surface. The bullet gets embedded into the block and moves 20m before coming to rest. The coefficient of friction between the block and the surface is ______.
(Given g = 10 m/s²)

• 0.25
• 0.50
• 0.65
• 0.90

3.

A particle of charge \(-q\) and mass \(m\) moves in a circle of radius \(r\) around an infinitely long line charge of linear density \(+\lambda\). Then the time period will be given as:

• \( T = 2\pi r \sqrt{\frac{m}{2kq}} \)

• \( T^2 = \frac{4\pi m r^3}{2kq} \)

• \( T = \frac{1}{2\pi r} \sqrt{\frac{m}{2kq}} \)

• \( T = \frac{2kq}{m} \)

4.

A body of m kg slides from rest along the curve of vertical circle from point A to B in friction less path. The velocity of the body at B is :

(Given, \( R = 14 \, \text{m}, \, g = 10 \, \text{m/s}^2 \, \text{and} \, \sqrt{2} = 1.4 \))

• 19.8 m/s
• 21.9 m/s
• 16.7 m/s
• 10.6 m/s

5.

A solid cylinder is placed gently over an incline plane of inclination \(60°\). The acceleration of cylinder when it start rolling without slipping is \(\frac{g}{\sqrt x}\) where \(μ\) is the coefficient of friction. [take \(g\) = \(10\;m / (s ^ 2)\) ]

6.

A cubic block of mass $ m $ is sliding down on an inclined plane at $ 60^\circ $ with an acceleration of $ \frac{g}{2} $, the value of coefficient of kinetic friction is:

• \( \sqrt{3} - 1 \)
• \( \frac{\sqrt{3}}{2} \)
• \( \frac{\sqrt{2}}{3} \)
• \( 1 - \frac{\sqrt{3}}{2} \)
  

7.

A block of mass m slides down the plane inclined at angle \(30\degree\) with an acceleration \(\frac{g}{4}\). The value of the coefficient of kinetic friction will be:

• \(2\sqrt{3} - \frac{1}{2}\)
• \(\frac{1}{2\sqrt{3}}\)
• \(2\sqrt{3}+\frac{1}{2}\)
• \(\frac{\sqrt{3}}{2}\)

8.

A block of mass m is placed on a surface having vertical cross section given by \(y=\frac{x^2}{4}\). If coefficient of friction is 0.5, the maximum height above the ground at which block can be placed without slipping is:

• \( \frac{1}{4} m \)

• \( \frac{1}{2} m \)

• \( \frac{1}{6} m \)

• \( \frac{1}{3} m \)

9.

A car is moving on a horizontal curved road with radius 50 m. The approximate maximum speed of the car will be, if the friction coefficient between tyres and road is 0.34. (Take g = 10 m/s²):

• 13.4m/s

• 13m/s

• 22.4m/s

• 17m/s

10.

A block of mass 2 kg moving on a horizontal surface with speed of 4 ms^–1 enters a rough surface ranging from x = 0.5 m to x = 1.5 m. The retarding force in this range of rough surface is related to distance by F = –kx where k = 12 Nm^–1. The speed of the block as it just crosses the rough surface will be

• Zero
• 1.5 ms^–1

• 2.0 ms^–1

• 2.5 ms^–1

11.

Given below are two statements :
Statement (I) : The limiting force of static friction depends on the area of contact and independent of materials.
Statement (II) : The limiting force of kinetic friction is independent of the area of contact and depends on materials.
In the light of the above statements, choose the most appropriate answer from the options given below :

• Statement I is correct but Statement II is incorrect
• Statement I is incorrect but Statement II is correct
• Both Statement I and Statement II are incorrect
• Both Statement I and Statement II are correct

12.

A block of mass 100 kg slides over a distance of 10 m on a horizontal surface. If the coefficient of friction between the surfaces is 0.4, then the work done against friction (in J) is:

• 4500 J
• 50000 J
• 4200 J
• 4000 J

13.

A block of mass \(2\) \(kg\) is placed on a disc which is rotating at constant angular velocity \(4\) \(rad/sec\). Find the friction force in (N) between block and disc if block is not sliding.

• 32
• 34
• 36
• 38

14.

Consider a block kept on an inclined plane (inclined at $45^{\circ}$ ) as shown in the figure If the force required to just push it up the incline is 2 times the force required to just prevent it from sliding down, the coefficient of friction between the block and inclined plane $(\mu)$ is equal to :

• $0.50$
• $0.33$
• $0.25$
• $0.60$

15.

A heavy box of mass 50 kg is moving on a horizontal surface. If co-efficient of kinetic friction between the box and horizontal surface is 0.3 then force of kinetic friction is :

• 14.7 N
• 147 N
• 1.47 N
• 1470 N