It’s okay to say that the front hooks aren’t as strong as the rear ones, but if I use a truck to pull on a hook with 100,000 N of force, it’s mathematically identical to a situation where that same hook uses 100,000 N of force to pull on the same hook.
If a hook is designed for the mass of a truck, it is designed for the mass of similar trucks as well.
The problem here is that the physical position of the truck upped the amount of force required to move it. That may still have been with spec for the hook in question, but then the kid went and added an extra whack of force in the form of momentum from moving quickly in reverse.
Edit: On further review, I think I am just elaborating on your point
[quote=“Papasan, post:10, topic:50395, full:true”]Good argument for teaching the sciences in school, apparently that dude missed those classes.[/quote]I never learned this particular lesson in physics class, actually. Most of the time we just treated ropes as massless objects that exert a force on something else. We did cover impulse very briefly, but it barely got beyond “this is how you calculate impulse”.
I suppose it might subsequently be argued that I didn’t have a very good physics class, but on the other hand we had an awful lot of material to cover.
Yeah, you didn’t have a good class. This situation (two ropes and a weight) is covered in Halliday & Resnick as a wonderful way to demonstrate the difference between a slowly-increasing force and an impulse force.
But really-- the kid in the video’s a moron. Rule One (well, there are lots of Rule Ones) is to start gently and only increase your effort if you haven’t succeeded yet.
Pro Physics Tip: use your trigonometry and force vectors here. If you back up the powered truck slowly until the rope is taut, then have a couple people pull the middle of the rope at right angles to the rope’s length, you can apply quite a bit of additional force in the desired direction (i.e. pull the stuck truckout) for not much personal effort.
“Sciences” actually covers a lot of territory, perhaps in the future I will refer “exactly” which “sciences”, then comprehension of the post won’t be an issue for, or as well create such a challenge.
