PHYSICS
posted by Matthew Goldberg .
A 5630 kg open railroad car coasts along with a constant speed of 8.64 m/s on a level track. Snow begins to fall vertically and fills the car at a rate of 3.50 kg per minute. Ignoring friction with the tracks, what is the speed of the car after 94.8 min?

Lateral momentum remains the same if friction can be ignored.
331.8 kg of snow is added in 94.8 minutes.
5630*8.64 = (5630 + 331.8)*Vfinal
Solve for Vfinal.
I can't imagine frictionless motion on a railroad track that is piled high with snow. In the real world, you can't blindly make wrong assumptions just to make the problem solving easier. 
A man with a mass of 64.1 kg stands up in a 61kg canoe of length 4.00 m floating on water. He walks from a point 0.75 m from the back of the canoe to a point 0.75 m from the front of the canoe. Assume negligible friction between the canoe and the water. How far does the canoe move?