pickups. just six inches can knock you off your feet. >> most everybody's been in the ocean and been pounded by a huge wave, and they feel that force, they can get up until the water recedes. and moving water in a river, treatment, does not give you that release. it never releases. so that force is constantly on you, and you can't get up. that's where most of the drownings occur. >> you're trapped in your car and being carried away by a flash flood. what should be your first move? a, unbuckle your seat belt and open the window. b, push open the door and swim away from the car or c, keep the windows rolled up and stay with the car. >> you're not going to be able to push the door open against the weight of that water. remember how heavy that water is. remember it's an incompressible fluid. it doesn't just push side like you do the air when you open the door. so that door's pretty much going to be staying close. >> which makes b an impossible