I know this is probably a complete n00b question, but I have tried all over the www and couldn't find it explained. Correct any of these premises if they are wrong, maybe that's my problem, but... velocity is current speed and acceleration is change in speed. So, if something is moving at a constant speed, it's acceleration is zero. So if a car (say 2000kg) is travelling at a constant speed of say 70mph on the motorway, and I like to have a picnic in the center lane, and that car hits me, the force it exerts should be zero because F=2000 x 0 which is zero so no force exerted on me? Yet I'm still thinking I'd be in trouble.. So what would cause me trouble if not a force exerted on me.. I assume my misunderstanding is something very basic and obvious. Thanks.