Two objects collide elastically. The first has a mass of 5.00kg and a velocity of 8.00 m/s. The second has a mass of 2.50 kg and a velocity
of -4.00m/s. If the velocity of object 1 after the collision is -4.00m/s,
what is the velocity of object 2?

Explanation:

General formula

m1 * vi + m2*v2 = m1*v3 + m2*v4

Givens

m1 = 5

m2 = 2.5

v1 = 8 m/s

v2 = - 4 m/s

v3 = -4 m/s

v4 = x

Solution

5 * 8 - 2.5 * 4 = 5 * -4 + 2.5*x

40 - 10 = -20 + 2.5x

30 = - 20 + 2.5x

50 = 2.5x

x = 50/2.5

x = 20 m/s in the positive direction

Remark

Does this answer make sense? It should. You have 5 kg moving 8m/s in the plus direction. That's a lot of momentum. In addition after the collision, it turns around which is more momentum needed.

It has to give up that extra momentum to the 2.5 kg mass.

i dont think you are wrong for wanting to get even with someone who did you wrong.

(i'm an eye for an eye kind of person) but if this person hurt you in a sexual way, i dont suggest doing anything to him. he should be taken to the proper authorities, you could go to jail depending on what you do. if it was something small like your sibling took your spot on the couch, than yea, i would get even with him by taking one of his favorite snacks lol. but i dont suggest you doing anything illegal.

true tan speed = ang vel x radius