Friction PYQs Set 4 (PDF)

Set 4 of 6 · Questions 91-120 of 162

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Mere Teacher · Previous Year Questions NEET Physics · Friction · Set 4 (Q91-120)
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91. $A wooden block, initially at rest on the ground, is pushed by a force which increases linearly with time t . Which of the following curve best describes acceleration of the block with time:$ (1) (2) (3) (4) 92. $Two blocks of masses ' M' and ' m' are placed on one another on a smooth horizontal surface as shown in the figure. The force ' F' is acting on the mass ' M' horizontally during time interval ' t'. Assuming no relative sliding between the blocks, the work done by friction on the blocks is \dots \dots$ (1) $\frac{Ft}{2 ( M + m )}$ (2) $\frac{M + m}{m t ^{2}}$ (3) $\frac{m F ^{2} t ^{2}}{2 ( M + m ) ^{2}}$ (4) $\frac{F ^{2} t ^{2}}{( M + m )}$ 93. $Two masses m_{1} = 5kg and m_{2} = 10kg connected by an inextensible string over a frictionless pulley are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15. The minimum weight m that should be put on top of m_{2} to stop the motion is:$ (1) $43.3 kg$ (2) $10.3 kg$ (3) $18.3 kg$ (4) $27.3 kg$ 94. $Three blocks A, B and C of masses 4 kg, 2 kg and 1 kg respectively, are in contact on a frictionless surface as shown. If a force of 14 N is applied on the 4 kg block, then the contact force between A and B is$ (1) $2 N$ (2) $6 N$ (3) $8 N$ (4) $18 N$ 95. $A block of mass m is lying on a rough inclined plane having an inclination α = tan^{- 1} (\frac{1}{5}) . The inclined plane is moving horizontally with a constant acceleration of a = 2 ms^{- 2} as shown in the figure. The minimum value of coefficient of friction, so that the block remains stationary with respect to the inclined plane is (Take, g = 10 ms^{- 2})$ (1) $\frac{2}{9}$ (2) $\frac{5}{12}$ (3) $\frac{1}{5}$ (4) $\frac{2}{5}$ 96. $Three masses M = 100 kg, m_{1} = 10 kg and m2 = 20 kg are arranged in a system as shown in figure. All the surfaces are frictionless and strings are inextensible and weightless. The pulleys are also weightless and frictionless. A force F is applied on the system so that the mass m2 moves upward with an acceleration of 2 m s^{- 2} . The value of F is: (Take g= 10 m s^{- 2})$ (1) $3360 N$ (2) $3380N$ (3) $3120N$ (4) $3240N$ 97. $A block kept on a rough inclined plane, as shown in the in the figure, remains at rest upto a maximum force 2N down the inclined plane. The maximum external force up the inclined plane that does not move the block is 10N. The coefficient of static friction between the block and the plane is: [Take g = 10 m / s^{2}]$ (1) $\frac{3}{2}$ (2) $\frac{3}{4}$ (3) $\frac{1}{2}$ (4) $\frac{2}{3}$ 98. $Consider a block kept on an inclined plane (inclined at 45°) as shown in the figure. If the force required to just push it up the incline is 2 times the force required to just prevent it from sliding down, the coefficient of friction between the block and inclined plane (^{μ}) is equal to:$ (1) $0.33$ (2) $0.60$ (3) $0.25$ (4) $0.50$ 99. $Two fixed frictionless inclined planes making an angle 30º and 60º with the vertical are shown in the figure. Two blocks A and B are placed on the two planes. What is the relative vertical acceleration of A with respect to B?$ (1) $4.9 ms-2 in horizontal direction$ (2) $9.8 ms-2 in vertical direction$ (3) $Zero$ (4) $4.9 m s^{- 2} in vertical direction$ 100. $Three blocks are connected by massless strings on a frictionless inclined plane of 30^{\circ} as shown in the figure. A force of 104 N is applied upward along the incline to mass m_{3} causing an upward motion of the blocks. What is the acceleration of the blocks? (Assume, acceleration due to gravity, g = 10 m / s^{2})$ (1) $6.0 m / s^{2}$ (2) $4.5 m / s^{2}$ (3) $3.0 m / s^{2}$ (4) $1.5 m / s^{2}$ 101. $In the arrangement shown in the figure, the coefficient of friction between two blocks is 0.5 . The force of friction between the two blocks is (Assume that the 4 kg block is placed on a smooth horizontal surface.) (Acceleration due to gravity = 10 ms^{- 2} .)$ (1) $8 N$ (2) $10 N$ (3) $6 N$ (4) $4 N$ 102. $A block kept on a rough surface starts sliding when the inclination of the surface is ' θ ' with respect to the horizontal. The coefficient of static friction between the block and the surface is$ (1) $sin θ$ (2) $tan θ$ (3) $cos θ$ (4) $sec θ$ 103. $Calculate the acceleration of the block and trolly system as shown in the figure. The coefficient of kinetic friction between the trolly and the surface is 0.05. (g = 10 m / s^{2}, mass of the string is negligible and no other friction exists). [NEET 2020]$ (1) $1.25 m / s^{2}$ (2) $1.50 m / s^{2}$ (3) $1.66 m / s^{2}$ (4) $1.00 m / s^{2}$ 104. $A body of mass m is kept on a rough horizontal surface (coefficient of friction = μ). Horizontal force is applied on the body but it does not move. The resultant of normal reaction and the frictional force acting on the object is given F, where F is [NEET 2019]$ (1) $\| F \| = mg + μmg$ (2) $\| F \| = μmg$ (3) $∣ F ∣ \leq mg 1 + μ^{2}$ (4) $\| F \| = mg$ 105. $Consider a system of two masses and a pulley shown in the figure. The coefficient of friction between the two blocks and also between block and table is 0.1 . Find the force F, that must be given to the 0.8 kg block such that it attains accelerations of 5 m / s^{2} . (Assume, acceleration due to gravity, g = 10 m / s^{2} .)$ (1) $6.4 N$ (2) $7.1 N$ (3) $6.0 N$ (4) $7.8 N$ 106. $As shown in the figure a block of mass 10 kg lying on a horizontal surface is pulled by a force F acting at an angle 30°, with horizontal. For μ_{s} = 0.25, the block will just start to move for the value of F: [Given g = 10 m s^{- 2}]$ (1) $33.3N$ (2) $25.2 N$ (3) $20N$ (4) $35.7 N$ 107. $A system containing masses and pulleys connected on an inclined plane is shown in the figure. If the system is in equilibrium then the value of m is$ (1) $1 kg$ (2) $0.5 kg$ (3) $0.75 kg$ (4) $0.25 kg$ 108. $A plank with a box on it at one end is gradually raised about the other end. As the angle of inclination with the horizontal reaches 30^{\circ}, the box starts to slip and slides 4.0 m down the plank in 4.0 s. The coefficients or static and kinetic friction between the box and the plank will be, respectively$ (1) $0.6 and 0.6$ (2) $0.6 and 0.5$ (3) $0.5 and 0.6$ (4) $0.4 and 0.3$ 109. $An object requires 500 N force to be pulled up on a 30^{\circ} frictionless smooth inclined plane at a constant speed. The weight of the object is$ (1) $5002 N$ (2) $1000 N$ (3) $10002 N$ (4) $5003 N$ 110. $A modern grand-prix racing car of mass m is travelling on a flat track in a circular arc of radius R with a speed v. If the coefficient of static friction between the tyres and the track is μ_{s}, then the magnitude of negative lift F_{L} acting downwards on the car is: (Assume forces on the four tyres are identical and g = acceleration due to gravity)$ (1) $m (\frac{v ^{2}}{μ _{s} R} + g)$ (2) $m (\frac{v ^{2}}{μ _{8} R} - g)$ (3) $m (g - \frac{v ^{2}}{μ _{s} R})$ (4) $- m (g + \frac{v ^{2}}{μ _{s} R})$ 111. $A body is made to move up along an inclined plane of inclination 30^{\circ} and the coefficient of friction is 0.5 , then its retardation is (g - acceleration due to gravity)$ (1) $(\frac{2 + 3}{4}) g$ (2) $(\frac{2 - 3}{4}) g$ (3) $(\frac{2 - 3}{2}) g$ (4) $(\frac{2 + 3}{2}) g$ 112. $An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1 kg moves with a speed of 12 m s^{- 1} and the second part of mass 2 kg moves with 8 m s^{- 1} speed. If the third part flies off with 4 m s^{- 1} speed, then its mass is$ (1) $7 kg$ (2) $17 kg$ (3) $3 kg$ (4) $5 kg$ 113. $Sand is to be piled up on a horizontal ground in the form of a regular cone of a fixed base of radius R . Coefficient of static friction between the sand layers is μ . Maximum volume of the sand can be piled up in the form of cone without slipping on the ground is$ (1) $\frac{μ R ^{3}}{3 π}$ (2) $\frac{μ R ^{3}}{3}$ (3) $\frac{π R ^{3}}{3 μ}$ (4) $\frac{μπ R ^{3}}{3}$ 114. $A bead of mass m is located on a parabolic wire with its axis vertical and vertex directed towards downward as in figure and whose equation is x^{2} = ay. If the coefficient of friction is µ, the highest distance above the x-axis at which the particle will be in equilibrium is -$ (1) $µa$ (2) $µ^{2} a$ (3) $\frac{1}{4} µ^{2} a$ (4) $\frac{1}{2} µ a$ 115. $A large drum having radius R is spinning around its axis with angular velocity ω, as shown in figure. The minimum value of ω so that a body of mass M remains stuck to the inner wall of the drum, taking the coefficient of friction between the drum surface and mass M as μ, is:$ (1) $\frac{μg}{R}$ (2) $\frac{g}{2 μR}$ (3) $\frac{2 g}{μR}$ (4) $\frac{g}{μR}$ 116. $A block A of mass m_{1} rests on a horizontal table. A light string connected to it passes over a frictionless pulley at the edge of table and from its other end another block B of mass m_{2} is suspended. The coefficient of kinetic friction between the block and the table is μ_{k} . When the block A is sliding on the table, the tension in the string is$ (1) $\frac{( m _{2} + μ _{k} m _{1} ) g}{( m _{1} + m _{2} )}$ (2) $\frac{( m _{2} - μ _{k} m _{1} ) g}{( m _{1} + m _{2} )}$ (3) $\frac{m _{1} m _{2} ( 1 + μ _{k} ) g}{( m _{1} + m _{2} )}$ (4) $\frac{m _{1} m _{2} ( 1 - μ _{k} ) g}{( m _{1} + m _{2} )}$ 117. $Block A of mass 2 kg is placed over block B of mass 8 kg . The combination is placed over a rough horizontal surface. Coefficient of friction between B and the floor is 0.5 . Coefficient of friction between A and B is 0.4 . A horizontal force of 10 N is applied on block B. The force of friction between A and B is (g = 10 m s^{- 2})$ (1) $100 N$ (2) $40 N$ (3) $50 N$ (4) $zero$ 118. $When a body slides down on inclined plane with coefficient of friction μ, then its acceleration will be$ (1) $g (sin θ - μ cos θ)$ (2) $g (sin θ + μ sec θ)$ (3) $g (μ sin θ - cos θ)$ (4) $gμ (sin θ - cos θ)$ 119. $A body of mass 20 kg is moving on a rough horizontal plane. A block of mass 3 kg is connected to the 20 kg mass by a string of negligible mass through a smooth pulley as shown in the below figure. The tension in the string is 27 N . The coefficient of kinetic friction between the heavier mass and the surface is (g = 10 m / s^{2})$ (1) $0.025$ (2) $0.035$ (3) $0.35$ (4) $0.25$ 120. $Consider a block and trolley system as shown in figure. If the coefficient of kinetic friction between the trolley and the surface is 0.04 , the acceleration of the system in ms^{- 2} is : (Consider that the string is massless and unstretchable and the pulley is also massless and frictionless):$ (1) $3$ (2) $4$ (3) $2$ (4) $1.2$