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 Post subject: Rotation of Rigid Bodies
PostPosted: Sat, 21 Jun 2003 16:18:51 UTC 
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Joined: Sat, 21 Jun 2003 15:48:20 UTC
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Please help me with this problem! I am really having a hard time answering this question! Thanks a lot!

A straight piece of reflecting tape extends from the center of a wheel to its rim. You darken the room and use a camera and strobe unit that flashes once every 0.050 s to take pictures of the wheel as it rotates counterclockwise. You trigger the strobe so that the first flash (t=0) occurs when the tape is horizontal to the rightat an angular displacement of zero. For the following situations draw a sketch of the photo you will get for the time exposure over five flashes (at t=0, 0.050 s, 0.100 s, 0.150s, and 0.200 s) and graph theta versus t and omega versus t for t=0 to t=0.200 s.
a.) The angular velocity is constant at 10.0 rev/s.
b.) The wheel starts from rest with a constant angular acceleration of 25.0 rev/s squared.
c.) The wheel is rotating at 10.0 rev/s at t=0 and changes angular velocity at a constant rate of -50.0 rev/s squared.


Last edited by nikki18 on Tue, 24 Jun 2003 03:49:43 UTC, edited 1 time in total.

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 Post subject:
PostPosted: Mon, 23 Jun 2003 02:34:35 UTC 
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Joined: Sun, 22 Jun 2003 18:00:06 UTC
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Location: North TX
a. 10 rev/s = 20pi rad/s
let z = angular displacement
w_0 = initial angular velocity (which is constant)
z = w_0*t
z = (20pi rad/s)*t
plug in values for t...
at t = 0 s, z = 0 rad
at t = 0.05 s, z = 1 rad
at t = 0.10 s, z = 2 rad
and so on...

b. A = 25 rev/s^2 * 2pi rad/rev = 50pi rad/s^2
z = w_0*t + (1/2)A*t^2
since w_0 = 0 (starting from rest)
z = (1/2)A*t^2
z = (25pi rad/s^2)*t^2
plug in values for t as before

c. w_0 = 10 rev/s = 20pi rad/s
A = -50 rev/s^2 = -100pi rad/s^2
z = w_0*t + (1/2)A*t^2
z = (20pi rad/s)*t + (-50pi rad/s^2)*t^2
once again...plug in the desired values for t


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 Post subject: thanks again!
PostPosted: Mon, 23 Jun 2003 11:28:41 UTC 
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Joined: Sat, 21 Jun 2003 15:48:20 UTC
Posts: 23
Hello there skeeter!!

thanks for answering all my problems!

I hope you could help me once again!


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