a cyclist does work at the rate of 500w while riding. how much force does her foot push with, when she is traveling at 8.0 m/s?

Answer 1

power=force(distance)/time

force=power/velocity=500/8 N.

Answer 2

Because of the gear ratio between pedal and wheel rim I have no idea how fast her foot moves to make the bike go 8m/s. Different gears give different foot forces for the same bike speed.