JEE Main Friction Previous Year Questions with Solutions

Q1: During peddling of a bicycle, the force of friction exerted by the ground on the two wheels is such that it acts

(a) in the backward direction on the front wheel and in the forward direction on the rear wheel

(b) in the forward direction on the front wheel and in the backward direction on the rear wheel

(c) in the backward direction on both, the front and the rear wheels

(d) in the forward direction on both, the front and the rear wheels.

Q2: A block of mass 0.1 kg is held against a wall applying a horizontal force of 5N on the block. If the coefficient of friction between the block and the wall is 0.5, the magnitude of the frictional force acting on the block is

(a) 2.5N

(b) 0.98N

(c) 4.9N

(d) 0.49N

Q3: A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is 0.2. The weight of the block is-

(a) 20 N

(b) 50 N

(c) 100 N

(d) 2 N

Q4: A marble block of mass 2 kg lying on ice when given a velocity of 6 m/s is stopped by friction in 10s. Then the coefficient of friction is (consider g =10m/s)

(a) 0.02

(b) 0.03

(c) 0.06

(d) 0.01

Q5: A block P of mass m is placed on a horizontal frictionless plane. The second block of the same mass m is placed on it and is connected to a spring of spring constant k. The two blocks are pulled by a distance A. Block Q oscillates without slipping. What is the maximum value of the frictional force between the two block.

(a)kA/2

(b) kA

(c) μ_smg

(d) zero

Q6: Statement 1: A block of mass m starts moving on a rough horizontal surface with a velocity v. It stops due to friction between the block and the surface after moving through a certain distance. The surface is now tilted to an angle of 30°with the horizontal and the same block is made to go up on the surface with the same initial velocity v. The decrease in mechanical energy in the second situation is smaller than that in the first situation.

Statement-2: The coefficient of friction between the block and the surface decreases with the increase in the angle of inclination.

(a) Statement-1 and 2 are true and statement-2 is a correct explanation for statement-1

(b) Statement-1 and 2 are true and statement-2 is not a correct explanation for statement-1

(c) Statement-1 is true, statement-2 is false

(d) Statement-1 is false, statement-2 is true.

Q7: A block rests on a rough inclined plane making an angle of 30⁰ with the horizontal. The coefficient of static friction between the block and the plane is 0.8. If the frictional force on the block is 10 N, the mass of the block (in kg) is : (taken g =10 m/s²)

(a) 2.0

(b) 4.0

(c) 1.6

(d) 2.5

Q8. A smooth block is released at rest on a 45⁰ incline and then slides a distance d. The time taken to slide is n times as much to slide on a rough incline than on a smooth incline. The coefficient of friction is-

(a) μ_k= 1- 1/n²

(b) μ_s= 1+ 1/n²

(c) μ_k= 1+ 1/n²

(d) μ_s= 1- 1/n²

Q9: The upper half of an inclined plane with inclination Φ is perfectly smooth, while the lower half is rough. A body starting from rest at the top will again come to rest at the bottom, if the coefficient of friction for the lower half is given by

(a) 2 sinΦ

(b) 2 cosΦ

(c) 2 tanΦ

(d) tanΦ

Q10: Consider a car moving on a straight road with a speed of 100 m/s. The distance at which a car can be stopped is : (μ_k = 0.5)

(a) 800 m

(b) 1000 m

(c) 100 m

(d) 400 m

Q11: The minimum force required to start pushing a body up a rough (frictional coefficient μ) inclined plane F₁ while the minimum force needed to prevent it from sliding down is F₂. If the inclined plane makes an angle θ from the horizontal such that tan θ= 2μ then the ratio F₁/F₂ is

(a) 4

(b) 1

(c) 2

(d) 3

Q12: A body of mass m=10⁻² kg is moving in a medium and experiences a frictional force F=−kv². Its initial speed is v₀= 10 ms⁻¹. If, after 10 s, its energy is ⅛ mv₀², the value of k will be

(a) 10⁻³ kg m⁻¹

(b) 10⁻³ kg s⁻¹

(c) 10⁻⁴ kg m⁻¹

(d) 10⁻¹ kg m⁻¹ s⁻¹

Q13: A block of mass m is placed on a surface with a vertical cross-section given by y =x³/ 6. If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is

(a) ⅓ m

(b) ½ m

(c) ⅙ m

(d) ⅔ m

Q14: Given in the figure are two blocks A and B of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force F as shown. If the coefficient of friction between the blocks is 0.1 and between block B and the wall is 0.15, the frictional force applied by the wall on block B is

(a) 120 N

(b) 150 N

(c) 100 N

(d) 80 N

Q15: Two masses m₁= 5 kg and m₂= 10 kg, connected by an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of the horizontal surface is 0.15. The minimum weight m that should be put on top of m₂ to stop the motion is

(a) 27.3 kg

(b) 43.3 kg

(c) 10.3 kg

(d) 18.3 kg