Riddle of the Week: The Bicycle Problem
Difficulty level: Moderate
Michael Stillwell
By Jay Bennett
We've got a fun physics riddle for you this week, one that cyclists in particular might enjoy.
PROBLEM
You have a bicycle, and your friend is holding it up so that it will not fall over, but he is not applying any pressure to it in any direction. You rotate the crank so that one of the crank arms is facing straight down, and then you tie a length of string around that crank arm. The setup will look something like this:
Michael Stillwell
With your friend holding the bike up, you pull back on the string. Will the bike move forward, backward, or stay in the same spot?
HINT
Take a guess first! Then scroll down a little more if you really want the hint.
Hint: The bike's rear wheel will not skid.
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