Simple Machines - Compound Pulleys And Its Types - video Dailymotion

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00:00hi kids today we will learn how pulleys give us mechanical advantage so let's

00:09start we now already know what are pulleys and that pulleys can be fixed or

00:18movable compound pulleys are called block and tackle and is a combination of

00:27one or more movable pulleys now let's learn more about compound pulleys and

00:36mechanical advantage they offer here we have two wheels and a rope looped around

00:46them here 100 kg weight is equally supported by two pulleys and a very long

00:56rope and because of this setting you can lift it by pulling with a force of

01:04just 50 kg that is half the force otherwise required that is this compound

01:13pulley is giving you a mechanical advantage mechanical advantage is the

01:18measurement of the extent to which a simple machine multiplies a force here

01:25the two pulley system is multiplying the force applied by two that is you are

01:31applying a force of 50 kg and it is giving you a force of 100 kg so the

01:41greater the mechanical advantage the lesser is the force required but the

01:46distance to which the weight has to be pulled down will double that is the

01:53weight rises one meter here but now we have to pull the loose end of the rope

01:59twice as far that is by two meters now let's see a compound pulley having four

02:08pulley wheels here we have a compound pulley with four pulley wheels here 100

02:17kg weight is equally supported by four pulleys and an even longer rope this

02:24means you can lift it by pulling with a force of just 25 kg that is 1 4th of the

02:32force otherwise required so it's giving you a lot of mechanical advantage that

02:38is it's multiplying the force applied by you by four so it's giving mechanical

02:45advantage of four and we learned the bigger mechanical advantage the lesser

02:54the force you need but the greater the distance you have to use that force that

02:59is to raise the weight by one meter you have to pull the loose end of the rope

03:05by four meters now let's see some examples of finding mechanical advantage

03:12here we have one fixed pulley that is where pulley does not move at all and is

03:20fixed and the weight is attached to one end of the rope and the other end is

03:27free to be pulled by any person for pulling or lifting a 50 kg weight a

03:34force of 50 kg is required so no mechanical advantage is there that is

03:42this pulley system is not multiplying the force applied by you but yes it's

03:49just changing the direction in which the force is required to be applied you are

03:55applying force downwards whereas the weight is required to be lifted upwards

04:02next we have one movable pulley that is pulley is not fixed one end of the rope

04:10is fixed and the other end is required to be pulled by any person and pulley is

04:17in the center here the weight of the object is equally divided between the

04:24pulley and the fixed end of the rope and in order to lift a weight of 50 kg 25

04:32kg effort is required that is it is giving us a mechanical advantage here

04:39the force applied is being multiplied by two so we say mechanical advantage of

04:47two is there in case of one movable pulley next example here we have one

04:57fixed and one movable pulley that is a block and tackle system here one of the

05:06pulleys is attached or fixed to some support and one pulley is attached to

05:13the load in this case it takes 25 kg effort to lift 50 kg weight so this

05:21means the structure is multiplying the applied force by two that is it has

05:27mechanical advantage of two now here we have next an example it is two fixed and

05:35two movable pulleys this is a compound pulley set up to fix pulley wheels are

05:45attached to the fixed support and two movable ones are attached to the weight

05:53this setup would take 25 kg effort to lift the weight of 100 kg that is it's

06:03multiplying the applied force by four so it's giving the mechanical advantage of

06:09four so kids we learned that the more the number of pulley wheels the higher

06:17the mechanical advantage now let's see some examples of how pulleys are used in

06:25our daily life here these cleaners are using the pulley system to hang over

06:33like this and cleaning the building this is a big crane this too uses pulleys to

06:43lift heavy weights this is a primitive well here too a pulley system is used to

06:53pull water from the well rock climbing here two kids are using the pulley system

07:00to hang over and then climbing the rock here too the pulley system is being used

07:07to cross over the river valley so we have a lot of examples where pulleys are used in

07:15our daily life so kids today we learned about compound pulleys its types and

07:23their mechanical advantage now you may go ahead and take a quiz to learn more bye bye

Simple Machines - Compound Pulleys And Its Types

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