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## Homework Statement

"A bicyclist can coast down a 5° hill at a constant 7.0 km/h. Assume the force of friction (air resistance) is proportional to the speed v so that Fair = cv."

(a) Calculate the value of the constant c.

(b) Calculate the average force that must be applied in order to descend the hill at 22 km/h. The mass of the cyclist plus bicycle is 79 kg.

## Homework Equations

Newton's Laws

## The Attempt at a Solution

Since a=0, Ʃforce must=0.

Fair=Fg

Fg=mgsin(5°)=Fair

c=mgsin(5°)/v

I just can't figure out how to work around not having mass in this problem.

Any help would be greatly appreciated :)