Turn your head for a second and the world of babysitting quickly turns in a world of collisions.

A collision is defined ad an event where two or more objects approach and interact strongly for a brief second. And well, my little brother and sister have a tendency to run into each other. A lot. Most of the time this results in a elastic collision otherwise known as a bouncy collision. In this type of collusion my brother and sister run into each other and then bounce apart. In this collision kinetic energy is conserved. My little brother weighs 35 pounds which converts to about 16kg and my little sister weighs about 40 pounds which converts to about 18kg. Now the average child runs at 2.5 m/s. However my little sister is very clumsy so she likes to walk slower at more of a 2m/s. Now lets make a MOMNENTUM TABLE!!!! If my little sister runs into my little brother who is standing at rest we can determine the speed at which my sister is flung backwards assuming that my little brother falls backwards at oh lets say .5m/s (See attachment)

physics of babysitting.doc

Pintial (kg x m/s) Pfinal (kg x m/s) Alexander 16 x 0 = 0 16 x .5 = 8 Alexa 18 x 2 = 36 18 x ? =18? Total 36

8 + 18?

Now in order to solve for the final velocity of my sister we have to set the total initial momentum equal to the total final momentum. This action is legal thanks to the LAW OF CONSERVATION OF MOMENTUM. This law stats Pintial=Pfinal.

So 36= 8 +18? if we solve for ? we find the ?= 1.6m/s So my little sister is pushed backwards with a velocity of 1.6m/s after she collides into my brother. All thanks to the CONSERVATION OF MOMENTUM!!!!!