Airbag jackets? Your thoughts? (now other gear questions)

[G.Irish]

Imagine that I am swinging a baseball bat. I can hit a line drive 90mph fastball that comes off the bat at 150+mph pretty easy. Where does that extra speed come from? I can't move my arms at 150mph. The end of the barrel of the bat is moving a lot faster than I can move my arms/wrists in a swing, and there is a lot of momentum transfer because of the fact that I weigh a lot.

Uhh, the reason you can hit a ball that fast is because you are adding energy to the ball by swinging it. If you just held the bat out and let the ball hit it (bunt) then you obviously would not accelerate the ball. The other part of the equation is the fact that the bat weighs more than the ball. If it weighed the same and you swung the bat slower than the ball was traveling the ball would force the bat backwards.

In the case of the motorcyclist the only way he is getting accelerated is if energy is added to the motorcycle. If he hits a car traveling in the opposite direction then he could possibly go faster. Hitting a stationary object will change the direction of his motion but it does not give him more kinetic energy, even if he is on the end of a lever.