Question

A person on a bicycle is moving East at 15 m/s on a horizontal road. The total mass of the person plus the bicycle is 9.0 x 101 kg. The person stops pedaling and comes to rest in 12 s. Calculate the average force causing the bicycle to slow down.


I need a free body diagram for the following question

Answer 1

Referring to the figure,

There must be some force in opposite direction of motion so that bicycle come to rest.

total Mass, $M = 9*10^1 = 90 kg$

Speed of the motion, $V = 15m/s$

total time of the motion, $t = 12s$

Then acceleration, (magnitude)

$a = \frac{V}{t} = \frac{15}{12} = 1.25m/s^2$

then Force, $F = Ma = 90*1.25 = 112.5 N$