1. Not finding help here? Sign up for a free 30min 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!

Force exerted on bicycle to maintain cosntant speed

  1. Jan 17, 2012 #1
    1. The problem statement, all variables and given/known data
    A 70-kilogram cyclist develops 210 watts of power while pedaling at a constant velocity of 7 m/s east. What average force is exerted eastward on the bicycle to maintain this constant speed?
    m = 70kg
    W = 210 J
    V = 7 m/s
    F = ?

    2. Relevant equations



    3. The attempt at a solution
    The way I did this problem was by looking at my units. I'm trying to find force (newtons) when given mass (kilograms), watts (Joules per second), and velocity (meters per second). I know that watts in joules per second is equal to newtons times meters per second, which in turn, becomes newtons times velocity. In the end, I use watts equals newtons times velocity and solve for newtons, dividing watts by velocity (in this case, 210 watts divided by 7 meters per second). I end up with 30 N. Is this a correct way of doing the problem? Is there another way to do it with an equation and number crunching?
     
  2. jcsd
  3. Jan 17, 2012 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    That is perfectly correct. Work=Force*Distance, so dividing by unit time gives you Power=Force*Velocity. But that's pretty much what you have already worked out using the units. Paying attention to units is a great thing and you are doing that well.
     
  4. Jan 17, 2012 #3

    NascentOxygen

    User Avatar

    Staff: Mentor

    Looks like the mass of the cyclist, here, is just a red herring. :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Force exerted on bicycle to maintain cosntant speed
  1. Force exerted (Replies: 1)

  2. Exerted force? (Replies: 1)

Loading...