An object with cross section A is shot horizontally across frictionless ice. Its initial velocity is at . Air resistance is not negligible.
a. Show that the velocity at time t is given by the expression
b. A -wide, -high, car with a drag coefficient of hits a very slick patch of ice while going . If friction is neglected, how long will it take until the car’s speed drops to ? To ?
c. Assess whether or not it is reasonable to neglect kinetic friction.