Let’s say you’re doing 100 mph in a car and suddenly a downed tree, stopped the car, or person appears in the road up ahead and you need to slam on the brakes. How much more dangerous is that situation than when you’re doing 70 mph? Your intuition might tell you that 100 mph is only 30% more than 70 mph. But as this video shows, the important factor in stopping a car (or what happens to the car when it collides with something else) does not speed but energy, which increases at the square of speed. In other words, going from 70 mph to 100 mph more than doubles your energy…and going from 55 to 100 more than triples it.