Comments on: physics question about rotational velocity? http://antiquerecordplayers.info/physics-question-about-rotational-velocity.htm Wed, 08 Feb 2012 20:35:34 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: RickB http://antiquerecordplayers.info/physics-question-about-rotational-velocity.htm/comment-page-1#comment-2663 RickB Mon, 23 Nov 2009 14:07:16 +0000 http://antiquerecordplayers.info/physics-question-about-rotational-velocity.htm#comment-2663 a) "RPM" is "revolutions per minute." You need to convert that into "revolutions per second." If you think about it, the number of turns it can make in one second, must be a lot less than the number of turns it can make in a whole minute. In fact, if it can make "x" revolutions in a minute, then it can only make "x/60" revolutions in a second. They tell you how much "x" is: so just divide. (Note: even though you say "revolutionS" (with an "S") per second, that doesn't necessarily mean the thing can make a whole revolution in a second. The number of "revolutions" per second might be less than 1.) b) The answer to (a) tells you how many revolutions the player can make in 1 second. So, the number of revolutions it can make in 5 seconds must be 5 times as many. So, just multiply by 5. a) "RPM" is "revolutions per minute." You need to convert that into "revolutions per second."

If you think about it, the number of turns it can make in one second, must be a lot less than the number of turns it can make in a whole minute. In fact, if it can make "x" revolutions in a minute, then it can only make "x/60" revolutions in a second. They tell you how much "x" is: so just divide.

(Note: even though you say "revolutionS" (with an "S") per second, that doesn’t necessarily mean the thing can make a whole revolution in a second. The number of "revolutions" per second might be less than 1.)

b) The answer to (a) tells you how many revolutions the player can make in 1 second. So, the number of revolutions it can make in 5 seconds must be 5 times as many. So, just multiply by 5.

]]> By: Jeff H http://antiquerecordplayers.info/physics-question-about-rotational-velocity.htm/comment-page-1#comment-2664 Jeff H Mon, 23 Nov 2009 14:07:16 +0000 http://antiquerecordplayers.info/physics-question-about-rotational-velocity.htm#comment-2664 a) 45 rpm / 60 s/min = 0.75rev/s b) 5 x 0.75 = 3.75 revolutions a) 45 rpm / 60 s/min = 0.75rev/s

b) 5 x 0.75 = 3.75 revolutions

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