Phy 231

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an 18-wheeler travels down the highway with a speed of 50 km/hr. each wheel has a 30 cm radius and a mass of 16 kg. what is the total kinetic(translational and rotational) energy of all 18 wheels?

  • Phy 231 -

    v= 50 km/h = 50000/3600 =13.9 m/s
    If the wheel is disc, I =mR²/2;
    ω = v/R.
    Iω²/2 = m•R²•v²/2•2•R²= mv²/4

    KE=18(mv²/2 + Iω²/2) = 18(mv²/2 + Iω²/4)=
    =18•3• mv²/4=27•mv²/2

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