Q. A railroad boxcar that has " due east" momentum of 15,000 kgm/sec collides with and couples with a similar boxcar that has "due west" momentum of 20,000 kgm/sec. After the collision, the combination has ( ) kgm/sec total of momentum.
Q. A baseball is seen to pass upward by a window 21 above the street with a vertical speed of 13 . If the ball is thrown from the street, when will it hit the street again?