Ball a of mass 5. 0 kilograms moving at 20. Meters per second collides with ball b of unknown mass moving at 10. Meters per second in the same direction. After the collision, ball a moves at 10. Meters per second and ball b at 15 meters per second, both still in the same direction. What is the mass of ball b?.

It would have to be c or d

Maybe because he failed the classes or is very accelerated.

Which of the following is an example of an opposing signal? no examplthates given.   i would say, that traffic lights in a city at major intersections direct the flow of traffic in opposite directions so would be an example.also, stop signs on either side of the same street would be an example. at a train crossing, the light for allowing car traffic in opposite directions or not would be another example.