Newton's Laws of Motion PYQs Set 6 (PDF)

Set 6 of 7 · Questions 151-180 of 185

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Mere Teacher · Previous Year Questions NEET Physics · Newton's Laws of Motion · Set 6 (Q151-180)
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151. $A monkey of mass 50kg climbs on a rope which can withstand the tension (T) of 350N. If monkey initially climbs down with an acceleration of 4m/ s^{2} and then climbs up with an acceleration of 5m/ s^{2} . Choose the correct option (g = 10m/ s^{2})$ (1) $T = 700N while climbing upward$ (2) $T = 350 N while going downward$ (3) $Rope will break while climbing upward$ (4) $Rope will break while going downward$ 152. $In the fig shown, a cubical block is held stationary against a rough wall by applying force F then incorrect statement among the following is$ (1) $Frictional force f = Mg$ (2) $F = N, N is Normal reaction$ (3) $F does not apply any torque$ (4) $N does not apply any torque.$ 153. $A system as shown in figure is in equilibrium and is at rest. The spring and string are massless, now the string is cut. The acceleration of the masses 2 m and m just after the string is cut, will be$ (1) $\frac{g}{2} upwards, g downwards$ (2) $g upwards, \frac{g}{2} downwards$ (3) $g upwards, 2 g downwards$ (4) $2 g upwards, g downwards$ 154. $The force 'F' acting on a particle of mass 'm' is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from zero to 8 s is:$ (1) $24 Ns$ (2) $20 Ns$ (3) $12 Ns$ (4) $6 Ns$ 155. $Three forces acting on a body are shown in the figure. To have the resultant force only along the y ‐direction, the magnitude of the minimum additional force needed is$ (1) $\frac{3}{4} N$ (2) $3 N$ (3) $0.5 N$ (4) $1.5 N$ 156. $A rigid ball of mass m strikes a rigid wall at 60 \circ and gets reflected without loss of speed as shown in the figure. The value of impulse imparted by the wall on the ball will be$ (1) $mV$ (2) $2 mV$ (3) $\frac{mV}{2}$ (4) $\frac{mV}{3}$ 157. $A body of mass m is suspended by two strings making angles θ_{1} and θ_{2} with the horizontal ceiling with tensions T_{1} and T_{2} simultaneously. T_{1} and T_{2} are related by T_{1} = 3 T_{2}, the angles θ_{1} and θ_{2} are$ (1) $θ_{1} = 30^{\circ} θ_{2} = 60^{\circ} with T_{2} = \frac{3 mg}{4}$ (2) $θ_{1} = 45^{\circ} θ_{2} = 45^{\circ} with T_{2} = \frac{3 mg}{4}$ (3) $θ_{1} = 30^{\circ} θ_{2} = 60^{\circ} with T_{2} = \frac{4 mg}{5}$ (4) $θ_{1} = 60^{\circ} θ_{2} = 30^{\circ} with T_{2} = \frac{mg}{2}$ 158. $Two masses ' m1 ' and ' m_{2}' moving with velocities ' v1 ' and ' v2 ' in opposite directions collide elastically and after collision masses ' m1 ' and ' m_{2}' move with velocity ' v2 ' and ' v1 ' respectively. The ratio (\frac{v _{2}}{v _{1}}) is$ (1) $1.25$ (2) $1.5$ (3) $1$ (4) $0.75$ 159. $A body of mass 5 kg explodes at rest into three fragments with masses in the ratio 1 : 1 : 3. The fragments with equal masses fly in mutually perpendicular directions with speeds of 21 m / s . The velocity of heaviest fragment in m / s will be$ (1) $72$ (2) $52$ (3) $32$ (4) $2$ 160. $Three identical blocks are suspended on two identical springs one below the other as shown in figure. If thread is cut that supports block 1, then initially (choose one alternative only)$ (1) $The second block falls with zero acceleration$ (2) $The first block falls with maximum acceleration$ (3) $Both (a) and (b) are wrong$ (4) $Both (a) and (b) are correct$ 161. $Two masses as shown in the figure are suspended from a massless pulley The acceleration of the system when masses are left free is$ (1) $\frac{2 g}{3}$ (2) $\frac{g}{3}$ (3) $\frac{g}{9}$ (4) $\frac{g}{7}$ 162. $A monkey is descending from the branch of a tree with constant acceleration. If the breaking strength is 75% of the weight of the monkey, the minimum acceleration with which monkey can slide down without branch is$ (1) $g$ (2) $3 g /4$ (3) $g/4$ (4) $g/2$ 163. $A car is moving with velocity v at the top of a semicircular hill of radius 40 m such that the normal force on it is zero. Find the velocity (v) of the car. [Use, g = 10 ms^{- 2}]$ (1) $15 ms^{- 1}$ (2) $20 ms^{- 1}$ (3) $30 ms^{- 1}$ (4) $40 ms^{- 1}$ 164. $A particle of mass m is moving with a uniform velocity v_{1} . It is given an impulse such that its velocity becomes v_{2} . The impulse is equal to$ (1) $m [∣ ∣ v_{2} ∣ - ∣ v_{1} ∣ ∣]$ (2) $\frac{1}{2} m [v_{2}^{2} - v_{1}^{2}]$ (3) $m [v_{1} + v_{2}]$ (4) $m [v_{2} - v_{1}]$ 165. $An object of mass 3 kg is tied by a string of negligible mass to a ceiling and held such that the string is taut. The object is released suddenly such that the string remains taut. It's acceleration when released is (acceleration due to gravity = 9.8 ms^{- 2})$ (1) $3.5 ms^{- 2}$ (2) $4.9 ms^{- 2}$ (3) $7.5 ms^{- 2}$ (4) $6.9 ms^{- 2}$ 166. $A truck is stationary and has a bob suspended by a light string, in a frame attached to the truck. The truck, suddenly moves to the right with an acceleration of a. The pendulum will tilt$ (1) $to the left and angle of inclination of the pendulum with the vertical is sin^{- 1} (\frac{g}{a})$ (2) $to the left and angle of inclination of the pendulum with the vertical is tan^{- 1} (\frac{a}{g})$ (3) $to the left and angle of inclination of the pendulum with the vertical is sin^{- 1} (\frac{a}{g})$ (4) $to the left and angle of inclination of the pendulum with the vertical is tan^{- 1} (\frac{g}{a})$ 167. $A body of mass 1000 kg is moving horizontally with a velocity 6 m / s . If 200 kg extra mass is added, the final velocity (in m / s) is:$ (1) $6$ (2) $2$ (3) $3$ (4) $5$ 168. $Two forces of magnitude F have a resultant of the same magnitude F. The angle between the two forces is$ (1) $45°$ (2) $120°$ (3) $150°$ (4) $60°$ 169. $An object is subjected to a force in the north-east direction. To balance this force, a second force should be applied in the direction$ (1) $North-East$ (2) $South$ (3) $South-West$ (4) $West$ 170. $The resultant force of 5 N and 10 N cannot be$ (1) $12 N$ (2) $8 N$ (3) $4 N$ (4) $5 N$ 171. $When milk is churned, cream gets separated due to$ (1) $centripetal force$ (2) $centrifugal force$ (3) $frictional force$ (4) $gravitational force$ 172. $A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The impulse experienced by the body is$ (1) $MV$ (2) $1.5 MV$ (3) $2 MV$ (4) $zero$ 173. $A particle of mass M is moving in a horizontal circle of radius R with uniform speed v . When the particle moves from one point to a diametrically opposite point, its$ (1) $momentum does not change$ (2) $momentum changes by 2 Mv$ (3) $kinetic energy changes by M v^{2} 4$ (4) $kinetic energy changes by M v^{2}$ 174. $A smooth circular groove has a smooth vertical wall as shown in figure. A block of mass m moves against the wall with a speed v. Which of the following curve represents the correct relation between the normal reaction on the block by the wall (N) and speed of the block (v)?$ (1) (2) (3) (4) 175. $A force F = (40 i + 10 j) N acts on a body of mass 5kg. If the body starts from rest, its position vector r at time t=10s, will be;$ (1) $(100 i + 400 j) m$ (2) $(100 i + 100 j) m$ (3) $(400 i + 100 j) m$ (4) $(400 i + 400 j) m$ 176. $The figure represents the momentum time (p-t) curve for a particle moving along an axis under the influence of the force. Identify the regions on the graph where the magnitude of the force is maximum and minimum respectively? If (t_{3} - t_{2}) < t_{1} .$ (1) $c and a$ (2) $b and c$ (3) $c and b$ (4) $a and b$ 177. $A mass of 10 Kg is suspended by a rope of length 4 m from the ceiling. A force F is applied horizontally at the mid-point of the rope such that the top half of the rope makes an angle of 45^{\circ} with the vertical. Then F equals: (Take g = 10 m s^{- 2} and the rope to be massless)$ (1) $100 N$ (2) $90 N$ (3) $75 N$ (4) $80 N$ 178. $The tension in the spring is$ (1) $zero$ (2) $10 N$ (3) $2.5 N$ (4) $5 N$ 179. $Which of the following is the correct order of forces$ (1) $Weak < gravitational forces < strong forces (nuclear) < electrostatic$ (2) $Gravitational < weak < (electrostatic) < strong force$ (3) $Gravitational < electrostatic < weak < strong force$ (4) $Weak < gravitational < electrostatic < strong forces$ 180. $A balloon has mass of 10 g in air. The air escapes from the balloon at a uniform rate with velocity 4.5 cm/s. If the balloon shrinks in 5 s completely. Then, the average force acting on that balloon will be (in dyne).$ (1) $3$ (2) $9$ (3) $12$ (4) $18$