The wheels on the bus......
A bus has a body of mass , and four wheels, each of mass . The wheels are uniform circular disks which rotate about their centers of mass. The wheels roll without slipping as the bus drives.
If the kinetic energy of all four wheels combined is the same as the kinetic energy of the body, what is the ratio ?
The answer is 6.0.
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1 solution
Kinetic energy of a disc rolling = ½ m v 2 + ½ I w 2 = ¾ m v 2 , as v = r w , I = ½ m r 2
Thus, 4 × ¾ m v 2 = ½ M v 2 , giving us the answer as 6 .