Comments on: A record player’s needle is 6.5cm from the center of a 45-rpm record. What is the velocity of the needle? http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle Mon, 06 Feb 2012 22:02:45 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: to_700million_idiots http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle/comment-page-1#comment-1784 to_700million_idiots Sat, 06 Feb 2010 04:04:59 +0000 http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle#comment-1784 ignore them ... you meant relative velocity why do you find this hard? the radius is 6.5 so the perimeter of that circle is 2 Pi R and it covers that distance 45 times in a minute Dist=2x3.142x6.5 Time = 60/45 Velocity = D/T so we have 13 x Pi x 45 / 60 = 30.63 cm/second (or 18.378 m/min 0r 0.3063 metres/second)<br><b>References : </b><br> ignore them … you meant relative velocity

why do you find this hard?

the radius is 6.5
so the perimeter of that circle is 2 Pi R
and it covers that distance 45 times in a minute

Dist=2×3.142×6.5
Time = 60/45
Velocity = D/T

so we have 13 x Pi x 45 / 60 = 30.63 cm/second

(or 18.378 m/min 0r 0.3063 metres/second)
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]]> By: bob shark http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle/comment-page-1#comment-1783 bob shark Sat, 06 Feb 2010 03:23:59 +0000 http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle#comment-1783 Circumference is Pi times diameter Diameter is raidus time 2 = 13CM 13 x 3.1416 = 40.84 cm circumference. 40.84 x 45 rpm =1,837.836 Cm per min or 18.38 meters per min<br><b>References : </b><br> Circumference is Pi times diameter
Diameter is raidus time 2 = 13CM
13 x 3.1416 = 40.84 cm circumference.
40.84 x 45 rpm =1,837.836 Cm per min or 18.38 meters per min
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]]> By: rick994 http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle/comment-page-1#comment-1782 rick994 Sat, 06 Feb 2010 02:34:59 +0000 http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle#comment-1782 Technically the needle doesn't have a velocity with respect to earth because it doesn't move. The record spins while the needle sits. Does the question ask what the relative velocity of the needle is with respect the the record? Could be a trick question.<br><b>References : </b><br> Technically the needle doesn’t have a velocity with respect to earth because it doesn’t move. The record spins while the needle sits. Does the question ask what the relative velocity of the needle is with respect the the record? Could be a trick question.
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]]> By: opal1331 http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle/comment-page-1#comment-1781 opal1331 Sat, 06 Feb 2010 01:57:59 +0000 http://www.blueboyrecords.com/record-player-needle/a-record-players-needle-is-6-5cm-from-the-center-of-a-45-rpm-record-what-is-the-velocity-of-the-needle#comment-1781 The needle doesn't have any velocity, it's stationary, only the record is moving.<br><b>References : </b><br> The needle doesn’t have any velocity, it’s stationary, only the record is moving.
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