Work, Energy & Power PYQs Set 6 (PDF)

Set 6 of 9 · Questions 151-180 of 248

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions NEET Physics · Work, Energy & Power · Set 6 (Q151-180)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
151. $Two bodies of masses m_{1} and m_{2} are acted upon by a constant force F for a time t . They start from rest and acquire kinetic energies E_{1} and E_{2} respectively. Then \frac{E _{1}}{E _{2}} is$ (1) $\frac{m _{1}}{m _{2}}$ (2) $\frac{m _{2}}{m _{1}}$ (3) $1$ (4) $\frac{m _{1} m _{2}}{m _{1} + m _{2}}$ 152. $The potential energy of a system increases if work is done$ (1) $upon the system by a nonconservative force.$ (2) $by the system against a conservative force.$ (3) $by the system against a nonconservative force.$ (4) $upon the system by a conservative force.$ 153. $The heart of a man pumps 5 L of blood through the arteries per minute at a pressure of 150 mm of mercury. If the density of mercury be 13.6 \times 10^{3} kg / m^{3} and g = 10 m / s^{2}, then the power of heart in watt is$ (1) $1.70$ (2) $2.35$ (3) $3.0$ (4) $1.50$ 154. $A boat of mass 1000 kg goes from rest to speed 20.0 m / s in 5.0 s . The water exerts a constant drag force and the acceleration of the boat is constant. If the average power required by the boat is 45000 W, then the magnitude of the drag force is$ (1) $500 N$ (2) $750 N$ (3) $250 N$ (4) $1000 N$ 155. $A ball of mass 1 kg moves in a straight line with velocity v = c x^{a}, where c = 1 (SI unit) and α is a constant. If the work done by the net force during its displacement from x = 0 to x = 4 m is 128 J, then the α is$ (1) $1$ (2) $\frac{3}{2}$ (3) $2$ (4) $\frac{1}{2}$ 156. $A body of mass 2 kg is moving with a constant acceleration of (2 i + 3 j - k) ms^{- 2} . If the displacement made by the body is (3 i - j + 2 k) m then the work done is$ (1) $22 J$ (2) $2 J$ (3) $12 J$ (4) $10 J$ 157. $A particle of mass M, starting from rest, undergoes uniform acceleration. If the speed acquired in time T is V, the power delivered to the particle is$ (1) $\frac{M V ^{2}}{T}$ (2) $\frac{1}{2} \frac{M V ^{2}}{T ^{2}}$ (3) $\frac{M V ^{2}}{T ^{2}}$ (4) $\frac{1}{2} \frac{M V ^{2}}{T}$ 158. $A particle which is experiencing a force, given by F \to= 3 i \to - 12 j \to undergoes a displacement of d \to= 4 i \to . If the particle had a kinetic energy of 3J at the beginning of the displacement, what is its kinetic energy at the end of the displacement?$ (1) $9 J$ (2) $12 J$ (3) $10 J$ (4) $15 J$ 159. $If a rubber ball falls from a height h and rebounds upto the height of h/2. The percentage loss of total energy of the initial system as well as velocity ball before it strikes the ground, respectively, are:$ (1) $50 %, 2 gh$ (2) $50 %, gh$ (3) $40 %, 2 g h$ (4) $50 %, \frac{gh}{2}$ 160. $The de-Broglie wavelength of an electron is the same as that of a photon. If velocity of electron is 25 % of the velocity of light, then the ratio of K.E. of electron and K.E. of photon will be:$ (1) $\frac{1}{1}$ (2) $\frac{1}{8}$ (3) $\frac{8}{1}$ (4) $\frac{1}{4}$ 161. $Water falls from a height of 60 m at the rate of 15 \frac{kg}{s} to operate a turbine. The losses due to frictional forces are 10% of energy. How much power is generated by the turbine? (g = \frac{10 m}{s ^{2}})$ (1) $12.3 kW$ (2) $7.0 kW$ (3) $8. 1 kW$ (4) $10.2 kW$ 162. $Consider a force F = Kx^{3}, which acts on a particle at rest. The work done by the force for displacement of 2 m is (K = 2 Nm^{- 3})$ (1) $10 J$ (2) $4 J$ (3) $100 J$ (4) $8 J$ 163. $At any instant of time t, the displacement of any particle is given by 2 t - 1 (SI unit) under the influence of force of 5 N. The value of instantaneous power is (in SI unit) [NEET 2024]$ (1) $10$ (2) $5$ (3) $7$ (4) $6$ 164. $Two springs A and B having spring constant K_{A} and K_{B} (K_{A} = 2 K_{B}) are stretched by applyingforce of equal magnitude. If energy stored in spring A is E_{A} then energy stored in B will be$ (1) $2 E_{A}$ (2) $E_{A} /4$ (3) $E_{A} l 2$ (4) $4 E_{A} .$ 165. $The potential energy of a particle in a force field is U = \frac{A}{r ^{2}} - \frac{B}{r} where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is$ (1) $\frac{B}{2 A}$ (2) $\frac{2 A}{B}$ (3) $\frac{A}{B}$ (4) $\frac{B}{A}$ 166. $A boy ties a stone of mass 100 g to the end of a 2 m long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of 80 N. If the maximum speed with which the stone can revolve is \frac{K}{π} rev. / min. The value of K is: (Assume the string is massless and un stretchable)$ (1) $400$ (2) $300$ (3) $600$ (4) $800$ 167. $If the average terminal velocity of rain drop is 2 ms^{- 1}, then the energy transferred by rain to each square metre of the surface at a place which receives 100 cm of rain in a year is$ (1) $1 \times 10^{4} J$ (2) $1 \times 10^{3} J$ (3) $2 \times 10^{3} J$ (4) $2 \times 10^{4} J$ 168. $Two bodies of masses m and 4 m are moving with equal kinetic energies. The ratio of their linear momenta is$ (1) $1 : 2$ (2) $1 : 4$ (3) $4: 1$ (4) $1 : 1.$ 169. $A toy of mass 20 gat rest acquires a velocity (3 i - 2 j) ms^{- 1} in 2 seconds. Then the power of the toy is$ (1) $0.975 W$ (2) $0.325 W$ (3) $0.13 W$ (4) $0.065 W$ 170. $A position dependent force, F = (7 - 2 x + 3 x^{2}) N acts on a small body of mass 2 kg and displaces it from x = 0 to x = 5 m . The work done in joule is$ (1) $135$ (2) $270$ (3) $35$ (4) $70.$ 171. $A body of mass 1 kg begins to move under the action of a time dependent force F = (2 t i + 3 t^{2} j) N, where i and j are unit vectors along x and y axis. What power will be developed by the force at the time t ? (NEET‐I2016)$ (1) $(2 t^{3} + 3 t^{4}) W$ (2) $(2 t^{3} + 3 t^{5}) W$ (3) $(2 t^{2} + 3 t^{3}) W$ (4) $(2 t^{2} + 4 t^{4}) W$ 172. $A uniform chain has a mass m and length l . It is held on a frictionless table with one-sixth of its length hanging over the edge. The work done in just pulling the hanging part back on the table is$ (1) $\frac{mgl}{72}$ (2) $\frac{mgl}{36}$ (3) $\frac{mgl}{12}$ (4) $\frac{mgl}{6}$ 173. $A mass m is attached to a thin wire and whirled in a vertical circle. The wire is most likely to break when [NEET 2019]$ (1) $the wire is horizontal$ (2) $the mass is at the lowest point$ (3) $inclined at an angle of 60^{\circ} from vertical$ (4) $the mass is at the highest point$ 174. $Two masses A and B, each of mass M are fixed together by a massless spring. A force acts on the mass B asshown in figure. If the mass A starts moving away from mass B with acceleration ’ a ’, then the acceleration of mass B will be:$ (1) $\frac{F + Ma}{M}$ (2) $\frac{F - Ma}{M}$ (3) $\frac{Ma - F}{M}$ (4) $\frac{MF}{F + Ma}$ 175. $A body of mass (5 \pm 0. 5) kg is moving with a velocity of (20 \pm 0.4) m s^{- 1} . Its kinetic energy will be$ (1) $(1000 \pm0.14) J$ (2) $(500\pm0.14)J$ (3) $(500 \pm 140) J$ (4) $(1000 \pm 140) J$ 176. $A bob of mass m is suspended at a point O by a light string of length l and left to perform vertical motion (circular) as shown in figure. Initially, by applying horizontal velocity v_{0} at the point ' A ', the string becomes slack when, the bob reaches at the point ' D '. The ratio of the kinetic energy of the bob at the points B and C is .$ (1) $1$ (2) $2$ (3) $4$ (4) $3$ 177. $A bag of sand of mass 9.8 kg is suspended by a rope. A bullet of 200 g travelling with speed 10 m s^{- 1} gets embedded in it, then loss of kinetic energy will be$ (1) $4.9 J$ (2) $9.8 J$ (3) $14.7J$ (4) $19.6 J$ 178. $Potential energy (V) versus distance (x) is given by the graph. Rank various regions as per the magnitudes of the force (F) acting on a particle from high to low.$ (1) $F_{CD} > F_{AB} > F_{BC} > F_{DE}$ (2) $F_{CD} > F_{DE} > F_{AB} > F_{BC}$ (3) $F_{BC} > F_{CD} > F_{DE} > F_{AB}$ (4) $F_{BC} > F_{AB} > F_{DE} > F_{CD}$ 179. $When a rubber-band is stretched by a distance x, it exerts a restoring force of magnitude F = ax + b x^{2} where a and b are constants. The work done in stretching the unstretched rubber-band by L is:$ (1) $a L^{2} + b L^{3}$ (2) $\frac{1}{2} (a L^{2} + b L^{3})$ (3) $\frac{a L ^{2}}{2} + \frac{b L ^{3}}{3}$ (4) $\frac{1}{2} (\frac{a L ^{2}}{2} + \frac{b L ^{3}}{3})$ 180. $A block of mass m is kept on a platform which starts from rest with constant acceleration g /2 upward, as shown in fig. work done by normal reaction on block in time t is:$ (1) $- \frac{m g ^{2} t ^{2}}{8}$ (2) $\frac{m g ^{2} t ^{2}}{8}$ (3) $0$ (4) $\frac{3 m g ^{2} t ^{2}}{8}$