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: Force exerted on the pedals ?

  1. Oct 19, 2006 #1
    force exerted on the pedals...???

    -) A cyclist intends to cycle up a 7.00° hill whose vertical height is 122 m. Assuming the mass of bicycle plus person is 76.2 kg, calculate how much work must be done against gravity. I got this part by multipling the (m)(g)(d)= 91100
    If each complete revolution of the pedals moves the bike 5.00 m along its path, calculate the average force that must be exerted on the pedals tangent to their circular path. Neglect work done by friction and other losses. The pedals turn in a circle of diameter 34.6 cm.
    I really have no idea :confused: . so if u can help me with that
  2. jcsd
  3. Oct 19, 2006 #2
    Think about it. You know the required force at the wheels,.. and 1 rev of the pedel = 5 m,.. total path is known,... divide to get the amount of force at the wheels per 1 rev of the pedels,...next use torque conversion to get force at pedals,.. remember 5 m is the outer lever distance,.. so the pedel requires more force than at the wheels
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook