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: Determine the angular velocity in rad/s and degrees/s

  1. Mar 28, 2007 #1
    i think i have part a right (but who knows). i dunno about part b. any help is appreciated!

    1. The problem statement, all variables and given/known data
    1) a car is travelling at 80km/h, and is towing a trailer. the wheels of the trailer are 40cm in diameter.

    a) determine the angular velocity in rad/s and degrees/s

    radius = 40cm/2 = 20 cm
    distance travelled in 1 hr = 80km = 8,000,000
    1 hr = 3600s

    distance travelled in 1s = 8,000,000/3600 = 2,222.222

    #of rotation in 1s = 2222.222/20pi = 35.37

    angular velocity = 35.27 x 2pi = 70.74pi rads

    70.74pr x (180/pi) = 6,372 degrees per second

    b) through what angle does the tire turn in 60s? state your answer in radians and degrees

    for this one i could just go 35.37 x 60s = 2122.7
    360degrees x .7 = 252degrees?

    252degrees x (pi/180) rad = 4.4 rad

    ?

    and then i have to explain why radians are better than degrees in these types of questions. i havent the foggiest idea.

    ~Amy
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Mar 28, 2007 #2

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Circumfrence is [itex] \pi [/itex] d, not [itex] \pi [/itex] r
     
  4. Mar 29, 2007 #3
    thanks :smile:

    so:

    a) determine the angular velocity in rad/s and degrees/s

    radius = 40cm/2 = 20 cm
    distance travelled in 1 hr = 80km = 8,000,000
    1 hr = 3600s

    distance travelled in 1s = 8,000,000/3600 = 2,222.222

    #of rotation in 1s = 2222.222/40pi = 17.7

    angular velocity = 17.7 x 2pi = 35.4pi rads

    35.4pi x (180/pi) = 6,372 degrees per second

    b) through what angle does the tire turn in 60s? state your answer in radians and degrees

    17.68 x 60s = 1060.8
    360degrees x .8 = 288degrees?

    288degrees x (pi/180) rad = 5.0 rad?

    ~Amy
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook