Pulley with everyday things

Pulleys are simple machines we find all around us.

Let us build simple pulley with everyday things and understand how pulleys help us.
We will cut circles from the card sheet and paste these circles with their centers aligned.

Let's make a big hole with the thick needle. We will insert a small plastic piece of used refill. This will ensure smooth movement of pulley without any wobbling.

Needle acts as an axle around which pulley can move freely. 1 rupee coins in a plastic container is our load for this setup.

Let us use a water bottle as a stand.

I can lift 5 coins in the container with my hand and place it on the box. For this action, I have to apply a force of more than 0.2 N in upward direction

This is called load and I am applying effort to move the load.
Instead I can use pulley and pull the container upwards. This time also I have to use the same force. But the direction of force is downwards.

Pulley can change direction of the force though the same force needs to be applied. This is good when we have to lift a heavy load.

How can we be sure that force is slightly greater than the load ? Let us attach another container and find out. With 5 coins, the container on the left side is slightly lifted. With the 6th coin, it comes up. There is some friction near the pulley which has to be taken care of as well.

Let us add one more pulley and water bottle. Pulley at the top is fixed, while pulley with coins can move freely. With 10 coins in this container, only 5 coins are needed to lift it up and the 6th coin to lift it completely. Last coin takes care of friction as well as some weight of the second pulley.

With pulley, we need less effort to lift heavy load. But there is a catch. With half the effort, we can lift full load only half the distance. Let us do some analysis.

With a single fixed pulley, when forces are the same on both sides, distance covered by both containers is the same.

When one pulley is moving and the other one fixed, container on the right side covers a distance of 14 cm while container on the left side covers a distance of 7 cm. We could lift a load of 10 coins with the help of 6 coins of effort but only half the distance.

Try these different variations to understand more about working of pulleys.

Thank You.
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#simpleMachines
#mechanics
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Видео Pulley with everyday things канала Ravindra Godbole