An empty 2,500 kg train car is headed northbound at a velocity of 5 m/s. ahead of the first car, an empty 1,500 kg car is headed northbound on the same track at 1 m/s. the faster train bumps into the slower one, and they combine into one train. what is the velocity of the two-car train?

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.

If a simple machine reduces the strength of a force, what must be increased?

The law of the conservation of momentum says that the total momentum of any closed and isolated system cannot