π Inventions and machines π§ Machines and tools
Levers
π In short
A lever is one of the simplest and oldest machines, helping us lift heavy things with little effort. It's just a strong stick or bar resting on a point it turns around, called the pivot. The seesaw you sit on with your friend is a lever!
π€© Did you know?
- The lever is one of the six simple machines.
- A 300-kilogram stone can be lifted with much less effort using a 3-meter crowbar.
- A lever has three parts: the pivot, where the effort goes and where the load is.
- Other simple machines include the pulley, the wheel and the inclined plane.
π Find out more
π How do they help us?
The farther your hand is from the pivot, the less force you need to lift the load. That's why we can lift a heavy rock with a long stick.
π The seesaw
If a heavy child and a light child sit on a seesaw, they balance when the heavy one moves closer to the middle and the light one moves farther away. Try it with your friends!
π‘ Levers in our lives
Scissors are a lever, so are pliers, bottle openers and tweezers, and even your arm is a lever: the elbow is its pivot and the muscle pulls it.
π― Archimedes
The Greek scientist Archimedes said: βGive me a place to stand and a long enough lever, and I will move the Earth!β, to show how powerful a lever is.
𧩠Test yourself
1 What do we call the point a lever turns around?
2 Which of these tools is a lever?
3 Which picture shows βLeversβ?
π Discover more
π· Picture sources: Wikimedia Commons
- CR at Spanish Wikipedia Β· CC BY-SA 3.0
