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!

Radian Measurements

  1. Jan 19, 2008 #1

    Simple questions, and hopefully I can explain my query a bit better than others I have made. I'm just trying to think of any advantages for using radians instead of degrees? I know/think that degrees are an arbitrary unit but cannot think of any reasons for using 360.

    1. What are the advantages of using radians?

    2. If degrees are an arbitrary unit then, where did the number 360 come from? Is it some how related to time, with 60 being a multiple of 360.

    3. Am I correct in saying that to convert 1 degree to radians I would use, 1 x π/180, and if converting 1 radian to degrees, I would use 1 x 180/π

  2. jcsd
  3. Jan 19, 2008 #2
    Heuristically, if you have a definite radius of rotation, use radians; if you don't, use degrees. Thus, in rotating machinery, radian usage makes all the formulas much easier and, in surveying, degree usage makes the shots much easier.

    As to why 360, many folks think the Babylonians are to blame. They used a base 60 number system. Others have noted that many ancient folks (and some modern ones) think 12 is a magical number.

    I personally think gradients (that's the G in the DRG button of your calculator) got a bad rap and should be used more.

    And, yes, your conversions are accurate.
    Last edited: Jan 19, 2008
  4. Jan 19, 2008 #3
    Would it be true in saying that using radians is more specific to the actual circle you are measuring? As it is directly related to the circle, as it uses other parts of it, almost as a ration to determin it? Where as the degrees system is only reliant on dividing the circle into 360 pieces.

    Am I correct in saying that to convert 1 degree to radians I would use, 1 x π/180, and if converting 1 radian to degrees, I would use 1 x 180/π
  5. Jan 19, 2008 #4
    Radians are nice because there are 2*pi of them in a circle, and 2*pi*r is the circumference of a circle... that means that you can multiply the number of radians in an angle by the radius to calculate the length of the arc for any slice of a circle, which turns out to be useful quite often in applied physics problems.
  6. Jan 19, 2008 #5
    360 is great number. and what makes it great is the fact that it is divisible by 2,3,4,5,6,8....(many small and useful numbers)
  7. Jan 19, 2008 #6
    Well I think I'll be using them quite soon both in mechanics and in physics, so it's nice to have a little head start thanks.
  8. Jan 19, 2008 #7


    User Avatar
    Science Advisor
    Homework Helper

    Radians are required for trigonometric functions and calculus. For example
    [tex]\frac{d}{dx}\sin{x^2} = 2x\cos{x^2}[/tex]
    is only true if x is in radians.
  9. Jan 19, 2008 #8
    Yes, I think that we are moving onto more advanced trigonometry within the next few weeks, and I have also heard the teacher mention them.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook