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: Linear acceleration of bicycle

  1. Nov 10, 2008 #1
    1. The problem statement, all variables and given/known data
    A bicycle has wheels with a radius of 0.295 m. It accelerates uniformly and the rate of rotation of its wheels increases form 209 rpm to 265 rpm in a time of 20.7 s. What is the linear acceleration of the bicycle?
    ω=angular vel. α=angular accel.
    2. Relevant equations
    rev/min*2π*1/60s= rad/s
    α=Δω/Δt
    arad2*r
    atan=r*α
    atotal=√arad2+atan2

    3. The attempt at a solution
    First changed rpm to radian/s so ω1=21.89 radian/s and ω2=27.75 radian/s
    For α=Δω/Δt=(27.75-21.89)/20.7s=0.283 radians/s2
    Then got atan=0.295 m*0.283 radians/s2=0.0835 m*radians/s2
    But I don't know if I should use ω1 or ω2 for the arad?? Do you use both and add them together to use for atotal or the change in arad? Also, do I have to multiply the final total accel by 2 since there are two wheels?
     
  2. jcsd
  3. Nov 10, 2008 #2
    Why do you want to find the radial acceleration of the bike? That won't give you its linear acceleration at all. ;)
     
  4. Nov 10, 2008 #3
    Ahh... I gotcha. Thanks a lot. But do I need to multiply it by 2 since there are two wheels and it's asking for the whole bicycle? I know this is stupid but I only have one submission on my HW left so I need to get this one.
     
  5. Nov 10, 2008 #4
    No. You're fine by solving the acceleration of one wheel, as far as I'm concerned.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook