Friction PYQs Set 6 (PDF)

Set 6 of 6 · Questions 151-162 of 162

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Mere Teacher · Previous Year Questions NEET Physics · Friction · Set 6 (Q151-162)
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151. $An inclined plane making an angle of 30^{\circ} with horizontal is placed in a uniform horizontal electric field 200 N/C as shown in the figure. A body of mass 1 kg and charge 5 mC is allowed to slide down from rest at a height of 1 m . If the coefficient of frication is 0.2, find the time taken by the body to reach the bottom. (g = 9.8 m / s^{2}, sin 30^{\circ} = \frac{1}{2}; cos 30^{\circ} = \frac{3}{2})$ (1) $2.3 s$ (2) $0.46 s$ (3) $1.3 s$ (4) $0.92 s$ 152. $A small block of mass m slides down from the top of a frictionless inclined surface, while the inclined plane is moving towards left with constant acceleration a_{0} . The angle between the inclined plane and ground is θ and its base length is L . Assuming that initially the small block is at the top of the inclined plane, the time it takes to reach the lowest point of the inclined plane is____.$ (1) $\frac{2 L}{gsinθ - a _{0} cosθ}$ (2) $\frac{4 L}{g cos ^{2} θ - a _{0} sinθcosθ}$ (3) $\frac{2 L}{gsin 2 θ - a _{0} ( 1 + cos 2 θ )}$ (4) $\frac{4 L}{gsin 2 θ - a _{0} ( 1 + cos 2 θ )}$ 153. $A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is 0.2. The weight of the block is$ (1) $2 N$ (2) $20 N$ (3) $50 N$ (4) $100 N$ 154. $One end of a massless spring of spring constant k and natural length l_{0} is fixed while the other end is connected to a small object of mass m lying on a frictionless table. The spring remains horizontal on the table. If the object is made to rotate at an angular velocity ω about an axis passing through fixed end, then the elongation of the spring will be:$ (1) $\frac{k - m ω ^{2} l _{0}}{m ω ^{2}}$ (2) $\frac{m ω ^{2} l _{0}}{k + m ω ^{2}}$ (3) $\frac{m ω ^{2} l _{0}}{k - m ω ^{2}}$ (4) $\frac{k + m ω ^{2} l _{0}}{m ω ^{2}}$ 155. $A system of two blocks of masses m = 2 kg and M = 8 kg is placed on a smooth table as shown in figure. The coefficient of static friction between two blocks is 0.5. The maximum horizontal force F that can be applied to the block of mass M so that the blocks move together will be:$ (1) $9.8N$ (2) $39.2N$ (3) $49N$ (4) $78.4N$ 156. $The time taken by an object to slide down 45° rough inclined plane is n times as it takes to slide down a perfectly smooth 45° incline plane. The coefficient of kinetic friction between the object and the incline plane is$ (1) $\frac{1}{1 - n ^{2}}$ (2) $1 - \frac{1}{n ^{2}}$ (3) $1 + \frac{1}{n ^{2}}$ (4) $1 - \frac{1}{n ^{2}}$ 157. $A block of mass M placed inside a box descends vertically with acceleration 'a'. The block exerts a force equal to one-fourth of its weight on the floor of the box. The value of ' a^{1} will be:$ (1) $\frac{g}{4}$ (2) $\frac{g}{2}$ (3) $\frac{3 g}{4}$ (4) $g$ 158. $A body of mass 10 kg is kept on a horizontal surface. The coefficient of kinetic friction between the body and the surface is 0.5 . A horizontal force of 60 N is applied on the body. The resulting acceleration of the body is about$ (1) $1 m s^{- 2}$ (2) $5 m s^{- 2}$ (3) $6 m s^{- 2}$ (4) $zero$ 159. $The weight of an aeroplane flying in the air is balanced by$ (1) $Vertical component of the thrust created by air currents striking the lower surface of the wings$ (2) $Force due to reaction of gases ejected by the revolving propeller$ (3) $Up thrust of the air which will be equal to the weight of the air having the same volume as the plane$ (4) $Force due to the pressure difference between the upper and lower surfaces of the wings created by different air speeds on the surfaces$ 160. $A uniform metal chain of mass m and length 'L' passes over a massless and frictionless pulley. It is released from rest with a part of its length 'l' is hanging on one side and rest of its length 'L-l' is hanging on the other side of the pulley. At a certain point of time, when l = \frac{L}{x}, the acceleration of the chain is \frac{g}{2} . The value of x is .........$ (1) $6$ (2) $2$ (3) $1.5$ (4) $4$ 161. $A block of mass M slides down on a rough inclined plane with constant velocity. The angle made by the incline plane with horizontal is 0. The magnitude of the contact force will be:$ (1) $Mg$ (2) $Mg cos θ$ (3) $M g sin θ + M g cos θ$ (4) $M g sin θ 1 + μ$ 162. $A block of mass m is placed on a smooth inclined wedge ABC of inclination θ as shown in the figure. The wedge is given an acceleration 'a' towards the right. The relation between a and θ for the block to remain stationary on the wedge is$ (1) $a = \frac{g}{cosec θ}$ (2) $a = g tan θ$ (3) $a = g cos θ$ (4) $a = \frac{g}{s in θ}$