Work, Energy & Power PYQs Set 6 (PDF)

Set 6 of 10 · Questions 151-180 of 294

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Mere Teacher · Previous Year Questions JEE Main Physics · Work, Energy & Power · Set 6 (Q151-180)
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151. $An athlete in the Olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range$ (1) $2 \times 1 0^{5} J - 3 \times 1 0^{5} J$ (2) $20,000 J - 50,000 J$ (3) $2,000 J - 5,000 J$ (4) $200 J - 500 J$ 152. $When a long spring is stretched by 2 cm, its potential energy is U . If the spring is stretched by 10 cm, the potential energy stored in it will be$ (1) $U /5$ (2) $5 U$ (3) $10 U$ (4) $2 5 U$ 153. $The work done in moving a body of mass 2 kg to a height of 4 m from the surface of the earth is (Acceleration due to gravity = 10 ms^{- 2})$ (1) $10 J$ (2) $20 J$ (3) $40 J$ (4) $80 J$ 154. $Which of the following is a incorrect statement?$ (1) $Work done by conservative force is equal to negative change in potential energy.$ (2) $Total energy of system is always conserved.$ (3) $Work done by non-conservative force in a closed path is equal to zero.$ (4) $In stable equilibrium, the potential energy is minimum.$ 155. $A motor pump lifts 6 tonnes of water from a well of depth 25 m to the first floor of height 35 m from the ground floor in 20 minutes. The power of the pump (in kW) is (g = 10 m s^{- 2})]$ (1) $6$ (2) $1.5$ (3) $12$ (4) $3$ 156. $A rifle bullet loses (\frac{1}{25}) th of its velocity in passing through a plank. The least number of such planks required just to stop the bullet is$ (1) $5$ (2) $10$ (3) $11$ (4) $13$ 157. $Two bodies of masses m_{1} and m_{2} are acted upon by a constant force F for a time t . They start from rest and acquire kinetic energies E_{1} and E_{2} respectively. Then \frac{E _{1}}{E _{2}} is$ (1) $\frac{m _{1}}{m _{2}}$ (2) $\frac{m _{2}}{m _{1}}$ (3) $1$ (4) $\frac{m _{1} m _{2}}{m _{1} + m _{2}}$ 158. $The potential energy of a system increases if work is done$ (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) $upon the system by a conservative force.$ 159. $The heart of a man pumps 5 L of blood through the arteries per minute at a pressure of 150 mm of mercury. If the density of mercury be 13.6 \times 10^{3} kg / m^{3} and g = 10 m / s^{2}, then the power of heart in watt is$ (1) $1.70$ (2) $2.35$ (3) $3.0$ (4) $1.50$ 160. $A boat of mass 1000 kg goes from rest to speed 20.0 m / s in 5.0 s . The water exerts a constant drag force and the acceleration of the boat is constant. If the average power required by the boat is 45000 W, then the magnitude of the drag force is$ (1) $500 N$ (2) $750 N$ (3) $250 N$ (4) $1000 N$ 161. $A ball of mass 1 kg moves in a straight line with velocity v = c x^{a}, where c = 1 (SI unit) and α is a constant. If the work done by the net force during its displacement from x = 0 to x = 4 m is 128 J, then the α is$ (1) $1$ (2) $\frac{3}{2}$ (3) $2$ (4) $\frac{1}{2}$ 162. $A body of mass 2 kg is moving with a constant acceleration of (2 i + 3 j - k) ms^{- 2} . If the displacement made by the body is (3 i - j + 2 k) m then the work done is$ (1) $22 J$ (2) $2 J$ (3) $12 J$ (4) $10 J$ 163. $A particle of mass M, starting from rest, undergoes uniform acceleration. If the speed acquired in time T is V, the power delivered to the particle is$ (1) $\frac{M V ^{2}}{T}$ (2) $\frac{1}{2} \frac{M V ^{2}}{T ^{2}}$ (3) $\frac{M V ^{2}}{T ^{2}}$ (4) $\frac{1}{2} \frac{M V ^{2}}{T}$ 164. $A particle which is experiencing a force, given by F \to= 3 i \to - 12 j \to undergoes a displacement of d \to= 4 i \to . If the particle had a kinetic energy of 3J at the beginning of the displacement, what is its kinetic energy at the end of the displacement?$ (1) $9 J$ (2) $12 J$ (3) $10 J$ (4) $15 J$ 165. $If a rubber ball falls from a height h and rebounds upto the height of h/2. The percentage loss of total energy of the initial system as well as velocity ball before it strikes the ground, respectively, are:$ (1) $50 %, 2 gh$ (2) $50 %, gh$ (3) $40 %, 2 g h$ (4) $50 %, \frac{gh}{2}$ 166. $The de-Broglie wavelength of an electron is the same as that of a photon. If velocity of electron is 25 % of the velocity of light, then the ratio of K.E. of electron and K.E. of photon will be:$ (1) $\frac{1}{1}$ (2) $\frac{1}{8}$ (3) $\frac{8}{1}$ (4) $\frac{1}{4}$ 167. $Water falls from a height of 60 m at the rate of 15 \frac{kg}{s} to operate a turbine. The losses due to frictional forces are 10% of energy. How much power is generated by the turbine? (g = \frac{10 m}{s ^{2}})$ (1) $12.3 kW$ (2) $7.0 kW$ (3) $8. 1 kW$ (4) $10.2 kW$ 168. $Consider a force F = Kx^{3}, which acts on a particle at rest. The work done by the force for displacement of 2 m is (K = 2 Nm^{- 3})$ (1) $10 J$ (2) $4 J$ (3) $100 J$ (4) $8 J$ 169. $At any instant of time t, the displacement of any particle is given by 2 t - 1 (SI unit) under the influence of force of 5 N. The value of instantaneous power is (in SI unit) [NEET 2024]$ (1) $10$ (2) $5$ (3) $7$ (4) $6$ 170. $Two springs A and B having spring constant K_{A} and K_{B} (K_{A} = 2 K_{B}) are stretched by applyingforce of equal magnitude. If energy stored in spring A is E_{A} then energy stored in B will be$ (1) $2 E_{A}$ (2) $E_{A} /4$ (3) $E_{A} l 2$ (4) $4 E_{A} .$ 171. $The potential energy of a particle in a force field is U = \frac{A}{r ^{2}} - \frac{B}{r} where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is$ (1) $\frac{B}{2 A}$ (2) $\frac{2 A}{B}$ (3) $\frac{A}{B}$ (4) $\frac{B}{A}$ 172. $A boy ties a stone of mass 100 g to the end of a 2 m long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of 80 N. If the maximum speed with which the stone can revolve is \frac{K}{π} rev. / min. The value of K is: (Assume the string is massless and un stretchable)$ (1) $400$ (2) $300$ (3) $600$ (4) $800$ 173. $If the average terminal velocity of rain drop is 2 ms^{- 1}, then the energy transferred by rain to each square metre of the surface at a place which receives 100 cm of rain in a year is$ (1) $1 \times 10^{4} J$ (2) $1 \times 10^{3} J$ (3) $2 \times 10^{3} J$ (4) $2 \times 10^{4} J$ 174. $Two bodies of masses m and 4 m are moving with equal kinetic energies. The ratio of their linear momenta is$ (1) $1 : 2$ (2) $1 : 4$ (3) $4: 1$ (4) $1 : 1.$ 175. $A toy of mass 20 gat rest acquires a velocity (3 i - 2 j) ms^{- 1} in 2 seconds. Then the power of the toy is$ (1) $0.975 W$ (2) $0.325 W$ (3) $0.13 W$ (4) $0.065 W$ 176. $A position dependent force, F = (7 - 2 x + 3 x^{2}) N acts on a small body of mass 2 kg and displaces it from x = 0 to x = 5 m . The work done in joule is$ (1) $135$ (2) $270$ (3) $35$ (4) $70.$ 177. $A body of mass 1 kg begins to move under the action of a time dependent force F = (2 t i + 3 t^{2} j) N, where i and j are unit vectors along x and y axis. What power will be developed by the force at the time t ? (NEET‐I2016)$ (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) $(2 t^{2} + 4 t^{4}) W$ 178. $A uniform chain has a mass m and length l . It is held on a frictionless table with one-sixth of its length hanging over the edge. The work done in just pulling the hanging part back on the table is$ (1) $\frac{mgl}{72}$ (2) $\frac{mgl}{36}$ (3) $\frac{mgl}{12}$ (4) $\frac{mgl}{6}$ 179. $Two particles having masses 4 g and 16 g respectively are moving with equal kinetic energies. The ratio of themagnitudes of their linear momentum is n : 2 . The value of n will be$ 180. $Two solids A and B of mass 1 kg and 2 kg respectively are moving withequal linear momentum. The ratio oftheir kinetic energies (K . E .)_{A} : (K . E .)_{B} will be \frac{A}{1} So the value of A will be$