posted by Anonymous .
Why can you exert a greater force on the pedals of a bike if you pull up on the handlebars?
Does it have anything to do with one of Newton's 3 laws? I'm not sure how to approach this question.
Stand on a scale and push on the ceiling :)
Third law. Force by man up on bars --> force down on man
Sum forces on the man who is not accelerating up or down
m g down + handlebar force down
force up on man = pedal force
net force = 0 so no change of momentum (F = m a = 0)
0 = m g down + handlebar force down - pedal up
pedal force UP on man = mg + handlebar force
so third law, equal and opposite force DOWN on pedal = m g + handlebar force
Thank you very much!
You are welcome.