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Centripetal and Tangitial Accelerations: Some Help please!

  1. Oct 25, 2006 #1
    Problem: The earth orbits the sun once a year (3.16 x 10^7 s) in a nearly circular orbit of radius 1.5 x 10^11 m. With respect to the sun, determine (a) the angular speed of the earth, (b) the tangential speed of the earth, and (c) the magnitude and direction of the earth's center centripetal acceleration.

    My Approach:

    (a) Finding Velocity:

    V = (1.5 x 10^11 m)/(3.16 x 10^7 s) = 4747 m/s

    --I did this because I'm assuming the earth's orbit of the sun is constant

    (b) Tangential Speed:

    V = rw = (1.5 x 10^11 m) (4747 m/s) = 7^14 .12 x 10m/s

    (c) Find Centripetal Acceleration:

    a(centripetal) = (V tangential)^2 / (radius) = (7.12 x 10^14 m/s)^2 / (1.5 x 10^11 m) = 3.38 x 10^18 m/s^2

    Please check my work and point out a quick way to fix something. I know this can be easy for any physics expert, but im just a beginner-so help me in simple terms :smile:
  2. jcsd
  3. Oct 25, 2006 #2
    Wasn't the first question about angular speed?

    This answer will be modified based on (a)...

    ...and so will this (and don't forget the direction). The formulae for b and c are correct.
  4. Oct 25, 2006 #3
    How Would Angular Speed be Calculated in this problem? we are only given the time and radius...Should i use one of the Big 3 equations?
  5. Oct 25, 2006 #4
  6. Oct 25, 2006 #5


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    Angular speed is not distance divided by time. It is the angular displacement divided by the time. Angular displacement is measured in radians.
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