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tmlrules

Joined: 26 Nov 2010
Posts: 2
Location: canada

 Posted: Fri Nov 26, 2010 9:16 pm    Post subject: Physics linear velocity to angular velocity, textbook wrong? Hi Consider a race car that moves with a speed of 200mi/h. If it travels on circular race track of circumference 2.5 mi, what is the cars angular velocity? First convert to meters/second and meters Then the way I tried to solve was to find the raduis from the circumference. c=(2pi)(r) r=(c)/(2pi) r=4023m/2pi r=640m Then v=wr w=v/r w=89.4 m/s / 640m w=0.139 rads/s which is angular velocity But the textbook got 0.022 rads/s they did w=v/r but they used the full circumference 4023 meters w=89.4 m/s / 4023m w=0.022 rads/s Why would they use the full circumference, when the raduis is supposed to be used? Thank you for answering, this is driving me crazy
hepcj
Site Admin

Joined: 23 Jun 2007
Posts: 125

 Posted: Sun Nov 28, 2010 12:24 pm    Post subject: I think that it is a mistake in the book. It should be v = r w. How you have done the problem is correct. It is not uncommon for a few mistakes to find there way into the answers, but it should have been checked.
tmlrules

Joined: 26 Nov 2010
Posts: 2
Location: canada

 Posted: Sun Nov 28, 2010 8:42 pm    Post subject: Thanks Thank you very much . I got the same answer in two different ways, but I could not be sure if it was correct because of the answers in the back of the book.
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