JERK

I had a funny day- and by that I mean, I laughed a lot. Also I tell you, physics is a very violent subject. A bit horrific too D: But the questions I encountered today were hilarious. I had a look at this random physics question in the moving about topic and it was on momentum. Basically it went: A car of mass 1.5 tonnes, travelling at 70km/h hits a pedestrian, who is stationary in the middle of the road. The car then has a final velocity of 20km/h. If the pedestrian weighs 50kg, what is their final velocity? LMAOOO WHAT THE CRAAZY WOULDN"T THE PEDESTRIAN BE KNOCKED FLAT ON THE GROUND AND DIE? Anyway, I answered the question and if I can remember, the pedestrian's final velocity was 416m/s WHICH IS QUITE FAST. LOOL. Oh and the fun doesn't stop there. There was another question and it went along these lines: Car A moving at 60km/h and Car B moving at 75km/h are both travelling along a road when a child runs across. Both cars attempt to avoid the child but hit the child, who has a mass of 40 kg. Car A hit the child at 27km/h and Car B hit the child at 54km/hr.  THE POOR KID!!!! After the first car hits the child, wouldn't they be lying on the floor with broken ribs at least? Does that mean the second car just RAN OVER the child and reduced the kid to...nothing???
ORRRR.. DID THEY BOTH HIT THE CHILD AT ONCE?????? D:
As I said, physics is incredibly violent.

Anyway, my imagination took me a little further. Remember ( a few posts ago), how I was curious about acceleration of acceleration, or basically, the change in acceleration? Well, I did a little random googling and I found out that the change in acceleration is in fact called JERK. IM NOT KIDDING GO WIKI IT!!! SO NOW I KNOW WHAT THE THIRD DERIVATIVE IS USED FOR!! OOFT what a smart cookie I am =P

OH and I made a new friend today.