Little Tammy lines up to tackle Jackson to (unsuccessfully) prove the law of conservation of momentum. Tammy’s mass is 34.0 kg and Jackson’s is 54.0 kg. Jackson is running at a velocity of 3.0 m/s. What must Tammy’s minimum velocity be in order to stop Jackson’s forward momentum?

So Tammy must move with speed 4.76 m/s in opposite direction of Jackson

Explanation:

As per law of conservation of momentum we know that there is no external force on it

So here we can say that initial momentum of the system must be equal to the final momentum of the system

now we have

final they both comes to rest so here we can say that final momentum must be zero

now we have

i don't understand. explain it clearly