1. Limited time only! Sign up for a free 30min personal 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!

Cyclist Power

  1. Jun 28, 2012 #1
    1. The problem statement, all variables and given/known data
    What power must a man of mass 85 kg have to bicycle 850m up a hill, inclined at 5.2° to the horizontal, at a constant speed of 15.6m/s? The force of friction on the man and the bicycle is 175N parallel to the incline.


    2. Relevant equations



    3. The attempt at a solution

    m= 85kg
    g=9.8m/ss
    v=15.6m/s
    θ= 5.2°

    F = 175N + mgsinθ
    = 175N + 75.497N Here I'm determining the forces required to overcome gravity and friction.
    = 250.497N

    P = F*v
    = 250.497N * 15.6m/s Here I took the calculated force and the velocity and determined the power.
    = 3900W

    How does it look?
     
    Last edited: Jun 29, 2012
  2. jcsd
  3. Jun 29, 2012 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    The way to work out if you have done well is to write out the reasoning that lead you to this calculation. It also makes it easier for an examiner to mark your work, which contributes to your ability to get a higher grade :)
     
  4. Jun 29, 2012 #3
    Thanks for the tip Simon. I added a couple lines describing the steps I took. It wasn't much.
     
  5. Jun 29, 2012 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Well OK - did that help you gain confidence with your work?

    How would you explain to a less experienced student why you chose that particular approach to solving the problem - or did you just guess and hope it turned out right?

    I know this sounds like an obtuse way to tell you you've done OK but you are at the next step where you need to be able to work out for yourself if you did right or not: the point of learning physics is to be able to solve problems that nobody knows the answer to so there is nobody to ask. The earlier you start learning how to tell if you've got it right the better you'll be at it - and the skill is general, you'll use it whatever you end up doing.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Cyclist Power
  1. Will The cyclist Skid? (Replies: 3)

  2. Cyclist up a plane (Replies: 8)

Loading...