physics question about rotational velocity?
when the author was a teenager, the rate of rotation for popular music records on a record player was 45 RPM
a) express the rotational velocity in rev/s
b) through how many revolutions doesw the record turn in a time of 5s?
please explain in an easily understandable way
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) 45 rpm / 60 s/min = 0.75rev/s
b) 5 x 0.75 = 3.75 revolutions