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What is the work to be done to increase the velocity of a car from 30kmh^(-1) to 60kmh^(-1), if the mass of the car is 1500kg? |
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Answer» Solution :Mass of the car `m=1500kg`, Initial velocity of car `U=30kmh^(-1)` `=(30xx1000m)/(60xx60s)` `=(25)/(3)ms^(-1)` Similarly, the final velocity of the car, `v=60kmh^(-1)` `=(50)/(3)ms^(-1)` Therefore, the initial kinetic energy of the car, `E_(kl)=(1)/(2)m u^(2)` `=(1)/(2)xx1500kgxx((25)/(3)ms^(-1))^(2)` `=(156250)/(3)J` The final kinetic energy of the car, `E_(kf)=(1)/(2)xx1500kgxx((50)/(3)ms^(-1))^(2)` `=(625000)/(3)J` Thus, the work done = Change in kinetic energy `=E_(kf)-E_(kl)` `=156250J` |
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