Friday, August 19, 2011

Pulleys


All right, so I know this comic isn’t really funny, but it’s just something I threw together in half an hour. I seriously need to get my homework done.

Pulleys

Ok, so pulleys help you to lift things. Pulleys are somewhat difficult to explain so this is going to be a longer post than usual. Yeah, so a pulley is just some string tied around a wheel. The wheel happens to be called the axle. You put your object on one end of the string and pull with the other. This is what it looks like:

Pulley

Yeah, I know it looks ugly. However, this diagram shows how a pulley basically works. You have to pull the rope down at a weight of 100kg if you want a 100kg thing to be lifted.

But then how DO pulleys work? If you just try to carry it anyway, you’ll still need a strength of 100kg to carry the weight. Well, to answer this question, is it easier to lift up a weight or to let it fall? Unless you happen to have some sort of bionic arm, it’s probably easier to let it fall. So pulleys work in the same way, because you’re pulling it down, it feels easier, even though it is the same.

So that’s basically everything on pulleys with one axle. However, most pulleys today have lots and lots of axles. Why? Well, more pulleys means less force is needed to move something. With 2 axles, you can actually halve the amount of force, so you only need 50kg of force to lift that 100kg weight. This is because there are 2 axles to help you take the weight. At the same time, you also need to pull the string twice as far, because while you only need 50kg of force to lift it up, you need twice the distance with that 50kg to lift it up COMPLETELY. It’s confusing stuff, so look at it this way:

With ONE axle, you need to pull the full weight

So with TWO axles, you only need 1/2 the weight

With THREE axles, you only need 1/4 the weight

and so on…

However there is a catch, if you wanted to lift a weight 1 metre in the air…

With ONE axle, you only need to pull the string 1 metre to lift it up 1 metre

With TWO axles, you need to pull the string 2 metres to lift it one metre

With THREE axles, you need to pull the string 4 metres to lift it one metre,

In a way, the extra distance you have to go when you have multiple axles is to balance out with the less force you need. So if you had a 100kg thing that you wanted to raise 1 metre, and you have 2 axles, then check the description above, and you will find that you only need to use 50kg of force but need to pull 2 metres. Then everybody knows that 2 X 50 = 100, which is the amount of weight you needed to lift at the start! Same goes for 3 axles, 4 X 25 is 100. If we moved on to 4 axles, we’d be getting decimals (12.5kg of weight, and 8 metres to pull) but we’ll still get 12.5 X 8 = 100. No matter how many axles you use, you will always be using the same amount of force! However, it feels easier because you use less force at one time. It’s like holding a balloon for one hour, instead of dumbbell for a minute. It’s makes lifting things much easier, even if you have to travel further.

Alright, so I’m going to stop here. I ‘m sorry if you’re too confused by all the talk about axles and weights and forces. The truth is that I can not really understand pulleys completely either. Unfortunately, for you guys reading my comics, there will probably be more, because my topic on science right now is machinery. However, not to leave on a sour note, we have one piece of good news:

Yes, that’s right, we’re are almost one month old! We’re going to have a tremendous ‘Monthday’ celebration, in which we’ll invite all the characters this month to come onto our celebration, in which we’ll have a gigantic cake, and lots of balloons, and disco dancing. You probably think that it is kind of lame to have a celebration just because our site is 1 month old, but as we are all 2D stick figures on comic strips, we don’t have much to do. Anyway, if you’re wondering why I haven’t introduced my editor in past comics, it’s because the only thing he wants to do is add pineapple hats to all my characters.


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