The Chair Lift
En vuxen och ett barn provar experimentet Hiss med block

The Chair Lift

Plan1,Fysik,Mekanik,Kraft & Rörelse
Can you lift yourself? You can in this experiment. The experiment illustrates tensile forces and gravity forces. Come and give yourself a lift to a level you may have thought was impossible.

You can lift yourself with the aid of a block and tackle. We use five pulleys here, one of which is used only to change the direction of the force. Each one of the other four pulleys halves the force that is needed to lift the person sitting on the chair. This means that you only have to lift one sixteenth of your weight, but you have to pull the rope a distance that is 16 times longer. This is the "golden rule" of mechanics: "What you win in force you have to pay for in travel".

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