Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Rotational motion question

  1. Nov 30, 2006 #1


    User Avatar

    Hey everyone, first time poster here:smile: It's a really great forum though!

    I can't seem to figure out this problem. If anyone could help that would be great.

    1.A bicycle has wheels with a diameter of 0.650 m. It accelerates uniformly and the rate of rotation of its wheels increases from 177rpm to 275rpm in a time of 18.5 s. Find the linear acceleration of the bicycle.

    I converted rpm to rad/s, and then found angular acceleration using a=vf-vi/t, but how do you find the linear acceleration given the diameter.

    And there's also this one:

    2.The tires of a car make 78.0 revolutions as the car reduces its speed uniformly from 92.5 km/hr to 55.9 km/hr. The tires have a diameter of 0.908 m. What was the angular acceleration?
  2. jcsd
  3. Nov 30, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper

    If you start with the definition of an angle as the ratio of arc length to radius, you see that the distance the center of a wheel moves when roilling without slipping is proportional to its angular displacement (rotation in radians). It follows that linear velocity is proportional to angular velocity and linear acceleration is probportional to angular acceleration. Can you come up with these relationships?
  4. Nov 30, 2006 #3
    The radius is half the diameter, isn't it? ;)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook