Answer:
= 5 m/s
Explanation: For collisions, use linear momentum, whose formula is: P = m.v and knowing the law of conservation states that momentum of a closed system is constant in time, i.e. initial momentum equals final momentum:


Suppose the referential for velocity is positive to the right:



The negative sign, in this case, indicates cart A is going to the left.
The magnitude of velocity of cart A is 5 m/s
B description, because the example describes what arachnids and spiders are
I'm not sure about number 1. Maybe: It was the happiest event.
2. The judge cautiously handed down her decision.
3. Mr. Majors was pressed hard to find an answer.