JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Question Bank

done Power Total Questions - 29

• question_answer1)
  If a force F is applied on a body and it moves with a velocity v, the power will be [CPMT 1985, 97; DCE 1999; UPSEAT 2004]
  A)
              \[F\times v\]     done clear
  B)
              \[F/v\] done clear
  C)
              \[F/{{v}^{2}}\]         done clear
  D)
              \[F\times {{v}^{2}}\] done clear
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• question_answer2)
  A body of mass m accelerates uniformly from rest to \[{{v}_{1}}\] in time \[{{t}_{1}}\]. As a function of time t, the instantaneous power delivered to the body is                                 [AIEEE 2004]
  A)
              \[\frac{m{{v}_{1}}t}{{{t}_{1}}}\]  done clear
  B)
              \[\frac{mv_{1}^{2}t}{{{t}_{1}}}\] done clear
  C)
                          \[\frac{m{{v}_{1}}{{t}^{2}}}{{{t}_{1}}}\]           done clear
  D)
                            \[\frac{mv_{1}^{2}t}{t_{1}^{2}}\]           done clear
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• question_answer3)
  A man is riding on a cycle with velocity 7.2 km/hr up a hill having a slope 1 in 20. The total mass of the man and cycle is 100 kg. The power of the man is
  A)
              200 W done clear
  B)
                175 W done clear
  C)
              125 W done clear
  D)
                98 W done clear
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• question_answer4)
  A 12 HP motor has to be operated 8 hours/day. How much will it cost at the rate of 50 paisa/kWh in 10 days
  A)
              Rs. 350/- done clear
  B)
                Rs. 358/- done clear
  C)
              Rs. 375/- done clear
  D)
                Rs. 397/- done clear
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• question_answer5)
  A motor boat is travelling with a speed of 3.0 m/sec. If the force on it due to water flow is 500 N, the power of the boat is                              [EAMCET 1982]
  A)
              150 kW done clear
  B)
                15 kW done clear
  C)
              1.5 kW done clear
  D)
                150 W done clear
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• question_answer6)
  An electric motor exerts a force of 40 N on a cable and pulls it by a distance of 30 m in one minute. The power supplied by the motor (in Watts)  is                              [EAMCET 1984]
  A)
              20        done clear
  B)
              200 done clear
  C)
              2          done clear
  D)
              10 done clear
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• question_answer7)
  An electric motor creates a tension of 4500 newton in a hoisting cable and reels it in at the rate of 2 m/sec. What is the power of electric motor                           [MNR 1984]
  A)
              15 kW done clear
  B)
                9 kW             P = Fv \[=4500\times 2=9000\,W=9\,kW\] done clear
  C)
              225 W done clear
  D)
                9000 HP done clear
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• question_answer8)
  A weight lifter lifts 300 kg from the ground to a height of 2 meter in 3 second. The average power generated by him is             [CPMT 1989; JIPMER 2001,02]
  A)
              5880 watt         done clear
  B)
              4410 watt done clear
  C)
              2205 watt done clear
  D)
                1960 watt done clear
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• question_answer9)
  Power of a water pump is 2 kW. If \[g=10\,m/{{\sec }^{2}}\], the amount of water it can raise in one minute to a height of 10 m is                   [CBSE PMT 1990; Kerala PMT 2004]
  A)
              2000 litre done clear
  B)
                1000 litre done clear
  C)
              100 litre done clear
  D)
                1200 litre done clear
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• question_answer10)
  An engine develops 10 kW of power. How much time will it take to lift a mass of 200 kg to a height of 40 m. \[(g=10\,m/{{\sec }^{2}})\]                    [CPMT 1992]
  A)
              4 sec    done clear
  B)
              5 sec done clear
  C)
              8 sec    done clear
  D)
              10 sec done clear
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• question_answer11)
  A car of mass ?m? is driven with acceleration ?a? along a straight level road against a constant external resistive force ?R?. When the velocity of the car is ?V?, the rate at which the engine of the car is doing work will be [MP PMT/PET 1998; JIPMER 2000]
  A)
              RV       done clear
  B)
              maV done clear
  C)
              \[(R+ma)V\] done clear
  D)
                \[(ma-R)V\] done clear
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• question_answer12)
  The average power required to lift a 100 kg mass through a height of 50 metres in approximately 50 seconds would be             [SCRA 1994; MH CET 2000]
  A)
              50 J/s   done clear
  B)
              5000 J/s done clear
  C)
              100 J/s done clear
  D)
                980 J/s done clear
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• question_answer13)
  From a waterfall, water is falling down at the rate of 100 kg/s on the blades of turbine. If the height of the fall is 100 m, then the power delivered to the turbine is approximately equal to   [KCET 1994; BHU 1997; MP PET 2000]
  A)
              100 kW done clear
  B)
                10 kW done clear
  C)
              1 kW    done clear
  D)
              1000 kW done clear
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• question_answer14)
  The power of a pump, which can pump 200kg of water to a height of 200m in 10sec is \[(g=10m/{{s}^{2}})\]          [CBSE PMT 2000]
  A)
              40 kW  done clear
  B)
              80 kW done clear
  C)
              400 kW done clear
  D)
                960 kW done clear
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• question_answer15)
  A 10 H.P. motor pumps out water from a well of depth 20m and fills a water tank of volume 22380 litres at a height of 10m from the ground. the running time of the motor to fill the empty water tank is \[(g=10m{{s}^{-2}}\]) [EAMCET (Engg.) 2000]
  A)
              5 minutes done clear
  B)
                10 minutes done clear
  C)
              15 minutes done clear
  D)
                20 minutes done clear
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• question_answer16)
  A car of mass 1250 kg is moving at 30m/s. Its engine delivers 30 kW while resistive force due to surface is 750N. What max acceleration can be given in the car           [RPET 2000]
  A)
              \[\frac{1}{3}\,m/{{s}^{2}}\] done clear
  B)
                \[\frac{1}{4}m/{{s}^{2}}\] done clear
  C)
              \[\frac{1}{5}\,m/{{s}^{2}}\] done clear
  D)
                \[\frac{1}{6}\,m/{{s}^{2}}\] done clear
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• question_answer17)
  A force applied by an engine of a train of mass \[2.05\times {{10}^{6}}kg\] changes its velocity from \[5m/s\] to 25\[m/s\] in \[5\] minutes. The power of the engine is [EAMCET 2001]
  A)
              \[1.025MW\] done clear
  B)
                \[2.05MW\] done clear
  C)
              \[5MW\]           done clear
  D)
              \[6MW\] done clear
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• question_answer18)
  A truck of mass 30,000kg moves up an inclined plane of slope 1 in 100 at a speed of 30 kmph. The power of the truck is (given \[g=10m{{s}^{-1}})\]                                   [Kerala (Engg.) 2001]
  A)
              25 kW  done clear
  B)
              10 kW done clear
  C)
              5 kW    done clear
  D)
              2.5 kW done clear
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• question_answer19)
  A 60 kg man runs up a staircase in 12 seconds while a 50 kg man runs up the same staircase in 11, seconds, the ratio of the rate of doing their work is                        [AMU (Engg.) 2001]
  A)
              6 : 5     done clear
  B)
              12 : 11 done clear
  C)
              11 : 10 done clear
  D)
                10 : 11 done clear
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• question_answer20)
  A pump motor is used to deliver water at a certain rate from a given pipe. To obtain twice as much water from the same pipe in the same time, power of the motor has to be increased to                           [JIPMER 2002]
  A)
              16 times done clear
  B)
                4 times done clear
  C)
              8 times done clear
  D)
                2 times done clear
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• question_answer21)
  A car of mass 1000 kg accelerates uniformly from rest to a velocity of 54 km/hour in 5s. The average power of the engine during this period in watts is (neglect friction) [Kerala PET 2002]
  A)
              2000 W done clear
  B)
                22500 W done clear
  C)
              5000 W done clear
  D)
                2250 W done clear
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• question_answer22)
  A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency the work done by the motor in one rotation will be                     [Kerala PET 2002]
  A)
              7.46 J  done clear
  B)
              7400 J done clear
  C)
              7.46 ergs done clear
  D)
                74.6 J done clear
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• question_answer23)
  An engine pumps up 100 kg of water through a height of 10 m in 5 s. Given that the efficiency of the engine is 60% . If \[g=10m{{s}^{-2}}\], the power of the engine is            [DPMT 2004]
  A)
              \[3.3kW\]         done clear
  B)
              \[0.33kW\] done clear
  C)
                \[0.033kW\] done clear
  D)
                \[33kW\] done clear
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• question_answer24)
  A force of \[2\hat{i}+3\hat{j}+4\hat{k}\ N\]acts on a body for 4 second, produces a displacement of \[(3\hat{i}+4\hat{j}+5\hat{k})m.\]The power used is          [Pb. PET 2001; CBSE PMT 2001]
  A)
              9.5 W   done clear
  B)
              7.5 W done clear
  C)
              6.5 W   done clear
  D)
              4.5 W done clear
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• question_answer25)
  The power of pump, which can pump 200 kg of water to a height of 50 m in 10 sec, will be  [DPMT 2003]
  A)
                          \[10\times {{10}^{3}}\,watt\]             done clear
  B)
                            \[20\times {{10}^{3}}\,watt\]             done clear
  C)
                            \[4\times {{10}^{3\,}}watt\]             done clear
  D)
                            \[60\times {{10}^{3}}\,watt\] done clear
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• question_answer26)
  From an automatic gun a man fires 360 bullet per minute with a speed of 360 km/hour. If each weighs 20 g, the power of the gun is                              [Pb. PET 2003]
  A)
                          \[600W\]                    done clear
  B)
                          \[300W\]                      done clear
  C)
                          \[150W\]                      done clear
  D)
                          \[75W\] done clear
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• question_answer27)
  An engine pump is used to pump a liquid of density \[\rho \] continuously through a pipe of cross-sectional area A. If the speed of flow of the liquid in the pipe is v, then the rate at which kinetic energy is being imparted to the liquid is
  A)
              \[\frac{1}{2}A\rho {{v}^{3}}\] done clear
  B)
                \[\frac{1}{2}A\rho {{v}^{2}}\] done clear
  C)
                          \[\frac{1}{2}A\rho v\]           done clear
  D)
                          \[A\rho v\] done clear
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• question_answer28)
  If the heart pushes 1 cc of blood in one second under pressure 20000 N/m2 the power of heart is [J&K CET 2005]
  A)
                          0.02 W             done clear
  B)
                            400 W             done clear
  C)
                          5 × 10?10 W                 done clear
  D)
                          0.2 W done clear
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• question_answer29)
  A man does a given amount of work in 10 sec. Another man does the same amount of work in 20 sec. The ratio of the output power of first man to the second man is [J&K CET 2005]          
  A)
                               1                      done clear
  B)
                          1/2           done clear
  C)
                          2/1                 done clear
  D)
                          None of these done clear
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