You set out to design a car that uses the energy stored in a flywheel consisting of a uniform 103-kg cylinder of radius R that has a maximum angular speed of 450 rev/s. The flywheel must deliver an average of 1.70 MJ of energy for each kilometer of distance. Find the smallest value of R for which the car can travel 300 km without the flywheel needing to be recharged.
My attempt:
U = 1/2 *I *w^2
w = 2 *pi *450
I = 1/12 *M*r^2
U = (1/24)103*r^2*(2pi450)^2
The total energy required to travel 300 km at 1.7 x10^6 so
U = 300 *1.7x10^6
I combined both U's together to try and solve for r
(1/24)*103*r^2*(2pi450) = 300 *1.7x10^6
r = sqrt (24*300*1.7x10^6) / 103*(2pi450)
r = sqrt (14.86)
r = 3.855 m
It told me I was wrong so any light as to why? Or am I just completely off on how to get the answer? Thanks in advance!
1 answer
Nevermind I was able to finally figure it out xP
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