a rain of mass 4000 metric tons is moving with a velocity of 18KMPH. with the application of a force, its velocities changes to 'v' in 2 mins. if the power of the engine is 10MW, the value of 'v' is? (ans : 90)

Dear Student,

Please find below the solution to the asked query:

Given information

mass of the train m=4000 metric tonns = 4×106 kg; initial velocity of the train Vi=18 kmph = 5 ms ; power of the engine is P=10 MW = 10×106 W and The time period is t=2 min = 120 sec. Let the final velocity of the train is Vf. Therefore, according to the conservation of energy,

K.Ef-K.Ei=P t  12mVf2-Vi2=10×106×120 12×4×106Vf2-52=1200×106  Vf2-25=600 Vf2=600+25 Vf2=252  Vf=25 ms  Vf=25×185 Vf=90 kmph


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