Hey guys! I was wondering if I could get some help with this question: A railway freight car that is carrying sand is traveling at a uniform velocity on a straight level track. A leak develops in the flat bottom, and the sand begins to pour out of a hole onto the ground. Assuming there aren't any external forces on the car (including friction), does the velocity of the car decrease, increase or remain the same? According to Newton's 1st law, it says that the velocity of an object will remain constant unless it's acted upon by an external or unbalanced force, which there isn't any in this question. However, I am a bit confused about the sand falling out. Do this affect the velocity of the car? Thanks if you can help me!