An older-model car accelerates from 0 to speed v in 9.0 s. A newer, more powerful sports car of the same mass accelerates from 0 to 3v in th

Question

An older-model car accelerates from 0 to speed v in 9.0 s. A newer, more powerful sports car of the same mass accelerates from 0 to 3v in the same time period. Assuming the energy coming from the engine appears only as kinetic energy of the cars, compare the power of the two cars. (Take Pnew and Pold as the powers of the new car and old car, respectively.)

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Adela 4 years 2021-07-28T21:45:03+00:00 1 Answers 17 views 0

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  1. bonexptip
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    2021-07-28T21:46:19+00:00
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    Answer:The new car has 9 times the power of the old car

    Explanation:

    Given data

    old car

    Mass =m

    Velocity =v

    Time to attain the velocity t= 9secs

    New car

    Mass =m (same as old car)

    Velocity =3v

    Time to attain the velocity t= 9secs

    We know that the kinetic energy expression is given as

    KE=1/2mv²

    KE for old car =1/2mv²J

    KE for new car =1/2m(3v)²

    =1/2m9v²J

    Now the expression for power is

    P= energy *time

    Pold = 1/2mv²*9

    4.5(mv²)Hp

    Pnew = 1/2m*9v²*9

    1/2m*81*v²

    40.5(m*v²)Hp

    Now comparing the powers of both cars

    Pnew/Pold =40.5mv²/4.5mv²

    Pnew/Pold = 9

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