Angular Kinematics: Calculating Wheel Rotation in 5s

AI Thread Summary
The discussion centers on calculating the total radians a wheel turns during a 5-second interval with an initial angular velocity of 20 rad/s, increasing to 40 rad/s under constant angular acceleration. The calculations show that the angular acceleration is 4 rad/s², leading to a total angular displacement of 150 radians. However, this answer does not match the provided options, raising questions about the accuracy of the problem statement or answer choices. Participants agree on the calculated value of 150 radians and suggest potential errors in the question or available answers. The conversation highlights the importance of verifying problem details in physics calculations.
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A wheel rotates about a fixed axis. Initial angular velocity of 20 rad/s.
During a 5 s interval the ang. velocity increases to 40 rad/s. (const angular acceleration) How many radians does the wheel turn in 5 s?

Having a bit of trouble, not quite sure why...
so I start out with
w = w0 + at
40 = 20 + a*5
a = 4

w^2 = w0^2 + 2*4*theta
theta = 150 radians

I thought that was the correct answer, however, that's not one of the choices. Anyone see what I'm doing wrong?
 
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I also have 150 radians... Are you sure you wrote the question word for word, or maybe there is an answer in degrees or something? It's also possible the book/test/homework/quiz/whatever it is, is wrong.
 
I second the 150 radians.
 

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