1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Rotation rate of hour hand on clock?

  1. Nov 19, 2009 #1
    What is the rotation rate in revolutions per minute of the hour hand of a clock?

    a.) 1/(12x60)
    b.) 1/24
    c.) 1/(24x60)
    d.) none of these

    I am not too sure how to answer this, i want to say its (a.) because it makes the most sense... ??any suggestions??
  2. jcsd
  3. Nov 19, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    How many minutes are there in 12hours (the time it takes to go around the clock?)
    If you have N minutes/revolution - how do you get to revolutions/minute?

    hint - if you are going 10miles/hour, what fraction of an hour does it take to go 1 mile
  4. Nov 19, 2009 #3
    there are 720 minutes in 12 hours..

    you invert(recipricol) of xmin/rev to get revolutions/min

    im still a little lost... :-/ how can we disprove some choices?
  5. Nov 19, 2009 #4
    one of the key differences in your choices are the numbers 12 and 24. What do they represent, and which one is relevant in the case of a full rotation of the hour hand?
  6. Nov 19, 2009 #5


    User Avatar
    Science Advisor
    Homework Helper

    Exactly so the answer is 1/(12*60) = 1/720 as you said.
    You don't need to disprove the others - they are just wrong!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook