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Pulley Mechanics: Part 1

Today we are going to be looking at one of the most important components in physics.

Without further ado, let's jump right in!


So for today's experiment you will need


  • Some clay

  • 1 Toothpick

  • 1 Plastic Bottle Cap

  • 2 Pencils

  • String

  • 1 Ring

  • Adhesive Tape




So the first step is to place a small piece of clay down.




The second step is to pierce the clay using two pencils. Try to make sure that the pencils are of the same height. Also make sure that the pencil tips are being pierced into the clay, and the flat ends are on top.




The third step is to pierce a hole into the center of the bottle cap and putting a toothpick through it. Make sure that the hole is big enough so that the cap can freely rotate around the toothpick.



The fourth step is the tape the toothpick to the tops of the pencils.



The fifth step is to carefully wrap the string around the bottle cap and then tying a small ring to one end of the string.


Giving a slight pull on the string on one end of the string pulls the ring up.





So why is a pulley useful??


To illustrate this, try a alternative setup where the ring is lifted with a string and without a pulley.


You will notice that the ring is slightly easier to pull up with the pulley.


Now, the ring ways very little, so the difference is not noticeable.

But in a real world scenario, this difference is massive. This is the main reason why pulleys are used in the first place.


To see why this works, we need to use a diagram.

The main principle behind the working class of a pulley is the force of tension.


Tension is basically a pulling force that is transferred by means of a rope, chain or string.





In a pulley there are two main forces at play.

Number one, is the pulling force of the user. This is what is the main catalyst to the lifting of the ring.

The second main force is tension.


In a rope, there can only be a pulling force and never a pushing force. Hence, a rope is always in tension.


When a user pulls in a rope, a downward force is generated.

Subsequently, that force is transferred through the rope in the form of tension.


This upward pointing tension force is what eventually pulls the ring up from the ground.


This next diagram clearly explains what I mean.




This is the working of a simple pulley.


It may look easy but this concept gets a lot more complex as we move up to complex pulleys.


Keep an eye out for part 2 in our pulley series!

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