- #1

integra2k20

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**General Question-- Compuing velocity of a center of mass**

## Homework Statement

A ball of mass 0.198 kg has a velocity of 1.47 i m/s; a ball of mass 0.309 kg has a velocity of -0.401 i m/s.They meet in a head-on elastic collision.

(a) Find their velocities after the collision.

(b) Find the velocity of their center of mass before and after the collision.

## Homework Equations

v1f = ((m1-m2)/(m1+m2))(v1i)+(2(m2)/(m1+m2))(v2i)

(m1)(v1i)+(m2)(v2i)=(m1)(v1f)+(m2)(v2f)

## The Attempt at a Solution

a.) Calculated velocities correctly: v1f = -.8106m/s, v2f = 1.0604m/s

b.) This is my problem

As i understand center of mass, it applies to an object as a whole, not a system. I have only been taught how to compute center of mass for an object with specific x and y dimensions, i have no idea how to find the center of mass of a system let alone the VELOCITY of the center of mass as is asked in this question.

my only guess is that since p = m(delta v) and p = m(v center of mass), that maybe the velocity of the center of mass is equal to the change in velocity?