I've been watching two in-duh-viduals once, loading an E28 engine onto their truck. They just put it over other stuff, at the very back of the truck bed. I've asked them "Aren't you guys going to strap it down?", to which they responded "Ah, don't worry, it's heavy, it'll just stay down".
Well, that was stupid even on the first sight, but I didn't realize how stupid it was until yesterday when I was trying to explain it to someone not quite technical.
So... here's how it looks in numbers:
Billy Bob and Bubba put engine that weighs 200kg onto the truck bed 4m away from the back of the passenger compartment.
10 minutes later, Bubba thinks he will make it through the intersection on the light that just turned red and floors it. He doesn't make it, though, and promptly T-bones a Corvette taking off his green, while still being at 40 km/h. 10 meters later the truck comes to complete stop.
- What was the force that the back of the passenger compartment was able to withstand if the dent the engine made was 50cm deep?
- How many times less would be the force on the engine if Billy Bob and Bubba had properly strapped it down, and stopped the truck on the red light, having started braking 100m away at 40km/h?