Answer to Question #109521 in Electricity and Magnetism for sdfa

Question

As an open train car rolls along a track, it is slowly filled with sand. Assume there is no friction, and that the car is just rolling along without receiving additional force. As the sand fills the car, what happens to the car's velocity?

Select one:
a. It increases, because momentum must be conserved and the mass of the car is increasing.
b. It decreases, but not because of any of the other reasons.
c. It decreases, because momentum must be conserved and the mass of the car is increasing.
d. It increases, but not because of any of the other reasons.
e. It decreases, because the frictional force increases as the mass increases.

Answer 1

c. It decreases, because momentum must be conserved and the mass of the car is increasing.