Sunday, June 7th, 2009

Physics: Finding angular speed and total length?

Moses S asked:


In a CD player, as the read head moves out from the center of the disc, the angular speed of the disc changes so that the linear speed at the position of the head remains at a constant value of about 1.3 m/s. Find the angular speed of the compact disc when the read head is at r = 2.0 cm and again at 5.6 cm. Information is recorded on a continous spiral track. Calculate the total length of the track for a CD that plays for 72 minutes.

speed reading

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One Response to “Physics: Finding angular speed and total length?”

Paschal H Says:
June 10th, 2009 at 5:47 pm

speed reading

First you need to find the circumferance at each radius. Be sure to work in meters.

Divide the linear speed (1.3 m/s) by the circumferance to get the revolutions per second. Next multiply by 2? to get radians per second.

For the last part, use:
X = VT
V = 1.3 m/s
T = 72*60 s
Solve for X

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