Phy 231
posted by Sally .
an 18wheeler 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?

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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