A 15,000kg railroad car moving at 7m/s to the right collides and sticks to another railroad car with a mass of 17,000kg that is moving in the same direction at 1.5m/s.
What is the velocity of the joined cars after the collision?

Which of the following changes to a pipe would increase the conductance by a factor of 12? 1.quadrupling the length and tripling the radius.2.reducing the length by a factor of and doubling the radius.3.tripling the length and reducing the radius by a factor of .4.reducing the length but a factor of and doubling the radius.

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

Which is the best for showing percentages of different types of cars sold(gas hybrid , electric , other ) in the united states ?