Friction PYQs Set 5 (PDF)

Set 5 of 6 · Questions 121-150 of 162

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Mere Teacher · Previous Year Questions NEET Physics · Friction · Set 5 (Q121-150)
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121. $A horizontal force 10 N is applied to a block A as shown in figure. The mass of blocks A and B are 2 kg and 3 kg respectively. The blocks slide over a frictionless surface. The force exerted by block A on block B is [NEET 2024]$ (1) $zero$ (2) $4 N$ (3) $6 N$ (4) $10 N$ 122. $The maximum value of the applied force F such that the block as shown in the arrangement does not move is (Acceleration due to gravity, g = 10 ms^{- 2})$ (1) $20 N$ (2) $15 N$ (3) $25 N$ (4) $10 N$ 123. $Two blocks A and B masses m_{A} = 1 kg and m_{B} = 3 kg are kepton the table as shown in figure. The coefficient of friction between A and B is 0.2 and between B and the surface of the table is also 0.2. The maximum force F that can be applied on B horizontally, so that the block A does not slide over the block B is : (Take g = 10 m / s^{2})$ (1) $8N$ (2) $16 N$ (3) $40 N$ (4) $12 N$ 124. $When an object is shot from the bottom of a long smooth inclined plane kept at an angle 60º with horizontal, it can travel a distance x_{1} along the plane. But when the inclination is decreased to 30º and the same object is shot with the same velocity, it can travel x_{2} distance. Then x_{1} : x_{2} will be:$ (1) $1 : 23$ (2) $1 : 2$ (3) $2 : 1$ (4) $1 : 3$ 125. $Three blocks A, B and C are pulled on a horizontal smooth surface by a force of 80 N as shown in figure The tensions T_{1} and T_{2} in the string are respectively:$ (1) $40 N, 64 N$ (2) $60 N, 80 N$ (3) $88 N, 96 N$ (4) $80 N, 100 N$ 126. $A block of mass m is placed on a surface with a vertical cross section given by y = \frac{x ^{3}}{6} . If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is:$ (1) $\frac{1}{6} m$ (2) $\frac{2}{3} m$ (3) $\frac{1}{3} m$ (4) $\frac{1}{2} m$ 127. $A cubic block of mass m is sliding down on an inclined plane at 60^{\circ} with an acceleration of \frac{g}{2}, the value of coefficient of kinetic friction is$ (1) $\frac{3}{2}$ (2) $\frac{2}{3}$ (3) $1 - \frac{3}{2}$ (4) $3 - 1$ 128. $In the figure the block of mass M is at rest on the floor. The acceleration with which a monkey of mass m should climb up along the rope of negligible mass so as to lift the block from the floor is,$ (1) $= (\frac{M}{m} - 1) g$ (2) $> (\frac{M}{m} - 1) g$ (3) $\frac{M}{m} g$ (4) $> \frac{M}{m} g$ 129. $A block of mass 1 kg is pushed up a surface inclined to horizontal at an angle of 60^{\circ} by a force of 10 N parallel to the inclined surface as shown in figure. When the block is pushed up by 10 m along inclined surface, the work done against frictional force is : (g = 10 m / s^{2})$ (1) $53 J$ (2) $5 J$ (3) $5 \times 10^{3} J$ (4) $10 J$ 130. $A block of mass m is in contact with the cart C as shown in the figure. The coefficient of static friction between the block and the cart is µ. The acceleration α of the cart that will prevent the block from falling satisfies$ (1) $α > \frac{m g}{μ}$ (2) $α > \frac{g}{μ m}$ (3) $α \geq \frac{g}{μ}$ (4) $α < \frac{g}{μ}$ 131. $A system consists of three masses m_{1}, m_{2} and m_{3} connected by a string passing over a pulley P . The mass m_{3} hangs freely and m_{2} and m_{1} are on a rough horizontal table (the coefficient of friction = μ). The pulley is frictionless and of negligible mass. The downward acceleration of mass m_{1} is: (Assume m_{1} = m_{2} = m_{3} = m)$ (1) $\frac{g ( 1 - g μ )}{9}$ (2) $\frac{2 g μ}{3}$ (3) $\frac{g ( 1 - 2 μ )}{3}$ (4) $\frac{g ( 1 - 2 μ )}{2}$ 132. $A block B is pushed momentarily along a horizontal surface with an initial velocity V. If μ is the coefficient of sliding friction between B and the surface, block B will come to rest after a time$ (1) $gμ / V$ (2) $g/V$ (3) $V/g$ (4) $V / (g μ) .$ 133. $A motor vehicle of mass 1000 kg is moving on a circular road having banking angle 30^{\circ} and coefficient of friction 0.2 . Then the normal reaction force on the motor vehicle is about (Acceleration due to gravity = 10 ms^{- 2})$ (1) $6750 N$ (2) $9060 N$ (3) $1070 N$ (4) $13055 N$ 134. $A block of mass slides on the wooden wedge, which in turn slides backward on the horizontal surface. The acceleration of the block with respect to the wedge is : Given m=8kg, M=16kg. Assume all the surfaces shown in the figure to be frictionless.$ (1) $\frac{4}{3} g$ (2) $\frac{6}{5} g$ (3) $\frac{3}{5} g$ (4) $\frac{2}{3} g$ 135. $A body of mass 2 kg is on an inclined plane of inclination 30^{\circ} and coefficient of friction is (\frac{1}{3}) . The minimum force required to move the body up the inclined plane is (Acceleration due to gravity = 10 ms^{- 2})$ (1) $5.77 N$ (2) $10 N$ (3) $20 N$ (4) $15 N$ 136. $Given in the figure are two blocks A and B of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force F as shown. If the coefficient of friction between the blocks is 0.1 and between block B and the wall is 0.15, the frictional force applied by the wall on block B is (Assume system in equilibrium):$ (1) $100N$ (2) $80N$ (3) $120N$ (4) $150N$ 137. $A block kept on a rough inclined plane, as shown in the figure, remains at rest upto a maximum force 2N down the inclined plane. The maximum external force up the inclined plane that does not move the block is 10 N. The coefficient of static friction between the block and the plane is: (Take g = 10 m/ s^{2})$ (1) $\frac{3}{4}$ (2) $\frac{1}{2}$ (3) $\frac{3}{2}$ (4) $\frac{2}{3}$ 138. $Maximum acceleration of the train in which a 50 kg box lying on its floor will remain stationary (Given : Co-efficient of static friction between the box and the train's floor is 0.3 and g = 10 m s^{- 2})$ (1) $5.0 m s^{- 2}$ (2) $3.0 m s^{- 2}$ (3) $1.5 m s^{- 2}$ (4) $15 m s^{- 2}$ 139. $A disc with a flat small bottom beaker placed on it at a distance R from its center is revolving about an axis passing through the center and perpendicular to its plane with an angular velocity ω . The coefficient of static friction between the bottom of the beaker and the surface of the disc is μ . The beaker will revolve with the disc if:$ (1) $R \leq \frac{μg}{2 ω ^{2}}$ (2) $R \leq \frac{μg}{ω ^{2}}$ (3) $R \geq \frac{μg}{2 ω ^{2}}$ (4) $R \geq \frac{μg}{ω ^{2}}$ 140. $All surfaces shown in figure are assumed to be frictionless and the pulleys and the string are light. The acceleration of the block of mass 2 kg is :$ (1) $g$ (2) $\frac{g}{3}$ (3) $\frac{g}{2}$ (4) $\frac{g}{4}$ 141. $At the moment t = 0, a time dependent force F = at (where a is constant equal to 1 Ns^{- 1}) is applied to a body of mass 1 kg resting on a smooth horizontal plane as shown in the figure. If the direction of this force makes an angle 45^{\circ} with the horizontal, then the velocity of the body at the moment it leaves the plane is (acceleration due to gravity = 10 m s^{- 2})$ (1) $50 ms^{- 1}$ (2) $502 r$ (3) $1002 ms^{- 1}$ (4) $100 ms^{- 1}$ 142. $A car is negotiating a curved road of radius R. The road is banked at an angle θ . The coefficient of friction between the tyres of the car and the road is μ_{s} . The maximum safe velocity on this road is$ (1) $\frac{g}{R} \frac{μ _{s} + t a n Θ}{1 - μ _{s} t a n Θ}$ (2) $\frac{g}{R ^{2}} \frac{μ _{s} + t a n Θ}{1 - μ _{s} t a n Θ}$ (3) $g R^{2} \frac{μ _{s} + t a n Θ}{1 - μ _{s} t a n Θ}$ (4) $g R \frac{μ _{s} + t a n Θ}{1 - μ _{s} t a n Θ}$ 143. $A block of mass m_{1} = 1 kg and another mass m_{2} = 2 kg, are placed together (see figure) on an inclined plane with angle of inclination θ. Various values of θ are given in List I. The coefficient of friction between the block m_{1} and the plane is always zero. The coefficient of static and dynamic friction between the block m_{2} and the plane are equal to µ = 0.3. In List II expression for the friction on block m_{2} given. Match the correct expression of the friction in List II with the angles given in List I, and choose the correct option. The acceleration due to gravity is denoted by g. List-I (P) θ = 5^{\circ} (Q) θ = 10^{\circ} (R) θ = 15^{\circ} (S) θ = 20^{\circ} List-II (1) m_{2} g sin θ (2) (m_{1} + m_{2}) g sin θ (3) μ m_{2} g cos θ (4) μ (m_{1} + m_{2}) g cos θ Code:$ (1) $P-1, Q-1, R-1, S-3$ (2) $P-2, Q-2, R-2, S-3$ (3) $P-2, Q-2, R-2, S-4$ (4) $P-2, Q-2, R-3, S-3$ 144. $The following is not the method of reducing friction$ (1) $using ball bearings$ (2) $applying grease$ (3) $applying paint$ (4) $forming a thin air cushion$ 145. $A ball rests upon a flat piece of paper on a table top. The paper is pulled horizontally but quickly towards right as shown. Relative to its initial position with respect to the table, the ball (1) remains stationary if there is no friction between the paper and the ball. (2) moves to the left and starts rolling backwards, i.e. to the left if there is a friction between the paper and the ball. (3) moves forward, i.e. in the direction in which the paper is pulled. Here, the correct statement/s is/are$ (1) $both (1) and (2)$ (2) $only (3)$ (3) $only (1)$ (4) $only (2)$ 146. $Three blocks are arranged as shown in which ABCD is a horizontal plane. Strings are massless and both pulley stands vertical while the strings connecting blocks m_{1} and m_{2} are also vertical and are perpendicular to faces AB and BC which are mutually perpendicular to each other. If m_{1} and m_{2} are 3 kg and 4 kg respectively. Coefficient of friction between the block m_{3} = 10 kg and surface is µ = 0.6 then, frictional force on m_{3} is -$ (1) $30 N$ (2) $40 N$ (3) $50 N$ (4) $60 N$ 147. $An iron block of sides 50 cm \times 8 cm \times15 cm has to be pushed along the floor. The force required will be minimum when the surface in contact with ground is:$ (1) $8 cm \times 15 cm surface$ (2) $50 cm \times 15 cm surface$ (3) $8 cm \times 50 cm surface$ (4) $Force is same for all surfaces$ 148. $A block of mass m = 2 kg is initially at rest on a horizontal surface. A horizontal force F_{1} = (6 N) i and a vertical force F_{2} = (10 N) j are then applied to the block. The coefficients of static friction and kinetic friction for the block and the surfaces are 0.4 and 0.25 , respectively. The magnitude of the frictional force acting on the block is (assume, g = 10 m / s^{2})$ (1) $2.5 N$ (2) $4.0 N$ (3) $3.3 N$ (4) $3.0 N$ 149. $In the given arrangement of a doubly inclined plane two blocks of masses M and m are placed. The blocks are connected by a light string passing over an ideal pulley as shown. The coefficient of friction between the surface of the plane and the blocks is 0.25 . The value of m, for which M = 10 kg will move down with an acceleration of 2 m / s^{2}, is : (take g = 10 m / s^{2} and (tan 37^{\circ} = 3/4)$ (1) $9 kg$ (2) $4.5 kg$ (3) $6.5 kg$ (4) $2.25 kg$ 150. $Consider a system of blocks X, A and B as shown in the figure. The blocks A and B have equal mass and are connected by a massless string through a massless pully. The coefficient of friction between block A and X or B and X is 0.5 . If block X moves on the horizontal frictionless surface what should be its minimum acceleration such that blocks A and B remain stationary. (g = acceleration due to gravity.)$ (1) $\frac{g}{3}$ (2) $3 g$ (3) $\frac{g}{4}$ (4) $3 g 4$