it's based on sir isaac newton's laws of physics. specifically, conservation of momentum.n one object strikes another, as in this demonstration, its momentum is transferred to the other. all things being equal, the speed of the first ball is equal to that of the last. the weight of the two cars, plus the friction between the tires and the road surface factor into the analysis. >> the coefficient of friction is basically just a measure of how slippery that surface is. so that's a very important piece. the other thing is the angles that are involved with approach and departure from the impact area for vehicles that are involved in a collision like this. >> scotland used surveying equipment to measure the distance the parked car moved after impact, as well as the angles of impact. a computer program performed the physics calculations. and the result? steve's jeep was traveling between 38 and 42 miles per hour when it hit the parked car, not 60 miles per hour as he claimed. these calculations also proved that steve had enough time to avoid hitting the parked car. >> he had sli

. >> it's a very exciting demonstration of newton's laws. >> sir isaac would be proud. we've got another camera angle showing that the terrifying tumble is, in fact, legit. the stunt gone wrong is performed by base jumper richard henrikson for the norwegian television show "normal madness". >> a lot of viral videos speak to our deepest instincts of wanting to see something but almost wincing or peaking between our fingers. i think any video that taps into that can be very powerful viewing. >> have no fear, that other angle reveals henrikson surviving the nearly 4,000-foot fall. luckily, he keeps his composure, opens his parachute, and lands with barely a scratch. it would have been much worse. henrikson's head comes within inches of slamming into the rock face. and seconds later, the apparatus comes crashing down, narrowly missing the base jumper. >> after this they probably had a talk about what we could have done differently. people make mistakes, but this is a big mistake! >> you don't have to be on a mountainside to risk life and limb. you can be in your own bedroom