8. Michelle is taking her little sister Sally for a toboggan ride. Sally and the toboggan have a combined mass of 40 kg. The coefficient of static friction between the toboggan and the snow is 0.25 and the coefficient of kinetic friction is 0.18.
a) What force must Michelle apply in order to get the toboggan moving?
b) Describe the frictional force and the motion of the toboggan if Michelle only applies a force of 70 N?
c) Once the toboggan starts to move, how much force does Michelle need to apply to keep it going at a constant speed?
d) Describe the frictional force and the motion of the toboggan if Michelle applies a force greater than the one calculated in question c)