How the fuck do these work? The force applied by the puller must be the same as the downward force of the pullee? So why is it easier than just living the barrel?
Working with gravity to pull down vs working against gravity to pull up
https://www.explainthatstuff.com/pulleys.html
>>17045626Basically this.But if the tension in the rope is the same is the force on the pulley itself equal or doubled?
>>17045648also what happens when you add more pulleys?
If I have a wire rope of diameter d1 made up of strands with diameter d2.Is there a way to calculate what minimum radius a pulley needs to have to minimise internal fatigue?
>>17045625It’s not really easier. I think you’re thinking of multiple pulleys.
>>17045689it is really easier because to pull something up with a pully you need grip strength and body weight, while to lift something up you need grip strength, thighs, core.the magnitudes of forces involved are the same, but that doesn't mean the effort is the same, unless you wanna argue that rolling something up a hill is exactly as hard as rolling the same thing down a hill
because work is an integral summed over a long period of time, so you get to redistribute it over time, but you still have to do the same work, easier here means impulse is lower, effort is spread over time, etc
>>17045691nice bait
>>17045625>So why is it easier than just living the barrel?You can just hang and your body weight does the lifting while lifting directly you must pull both the barrel and your own body weight.If you have a weak grip you can tie the rope around your hips and just sit, bodyweight does the lifting.This is without adding pulleys.
>>17045625Each pulley is essentially another person, but in physics we call the them dæmons. They share the load. One pulley = full load. Two pulleys = half loads. N pulleys = 1/N load.Ergo: Lots of Matt Dæmon’s body doubles can help with farm chores and apartment moving.You still need a truck. And you owe everyone pizza and beer afterwards.
>>17045625When you pull with pulley for really heavy stuff, you don't crouch or bend your arm/shoulder. You hold the rope, then step back with multiple people helping. 1. step back means friction, which is proportional to body weight2. using a rope allows multiple people to help conveniently (ergonomically)If you just do what >>17045625 picrel shows, it doesn't do much really. With that kind of rope climbing movement, the relevant bodyweight (arm weight) are only a few kg. If you try to crouch/bend while holding the rope, you get more bodyweight help, but you also need to have enough strength in your leg/torso to pull the rest.
lets say we tie off that rope.how much leverage do we achieve by grabbing it in the middle and pulling it sideways?
On a pure account of work=Force x distance, you do the same work with a pulley or directly lifting.But when you use a pulley, your own bodyweight does most of the lift and you pay later by having to stand up. So on average you perform the same labor with a longer distance and a lower force, hence easier.
it's called pull-ey because you pull it
>>17045777fuck, i meant distance, i am so used to odes and integration in the time domain i forgot you can integrate distances and vector valued paths
>>17045625Because humans are not 100% physically efficient and the biomechanics of using a pulley is better than the biomechanics of lifting the barrel yourself
>>17045625gravity assist
