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What is work? Physics definitions

By | 2017-08-17T11:00:59+00:00 August 17th, 2017|Physics|

Ancient Egyptian cattle plowing (Louvre Museum, Paris) You might think you know what work is, like homework, or having to pick up your room, right? But to scientists, work has a more definite meaning: work is force x distance. That means that you can measure work by measuring how much force, or energy, [...]

Wheel and axle – Simple machines – Physics

By | 2017-08-17T10:52:53+00:00 August 17th, 2017|Central Asia, Physics|

An Egyptian potter uses a pottery wheel, about 2000 BC Wheels do not exist in nature, and no animals use them except people. Even people didn't use wheels until the early Bronze Age, around 3500 BC, much later than the other simple machines (the lever and the inclined plane). The earliest evidence for people using wheels comes from Sumeria (modern [...]

Wedge – Simple machines – Physics

By | 2017-08-17T10:45:17+00:00 August 17th, 2017|Physics|

This stone hand-ax from Chennai, India is a kind of wedge. Like screws, wedges are really a kind of inclined plane, but they are so useful that people give them their own category. A wedge is two inclined planes back to back against each other. Wedges evolved on their own long before people. Sharp teeth are a [...]

Screw – Simple machines – Physics

By | 2017-10-14T16:35:54+00:00 August 17th, 2017|Physics, What|

A cider press with big wooden screws People always count screws as a separate kind of simple machine. But really screws are just one kind of inclined plane. They are such an important kind that we give them their own category. Like most other simple machines, screws also exist in nature. The hip joints of [...]

Movable pulley – Simple machines – Physics

By | 2017-08-17T10:05:45+00:00 August 17th, 2017|Physics|

Bike hoist pulleys A movable pulley is a way to use a pulley to make it easier to move heavy things - to get a mechanical advantage. In the picture, someone is trying to pull their bike up to the ceiling so it will be out of the way. They've used two fixed pulleys, attached to [...]

Pulley – Simple machines – Physics

By | 2017-08-17T10:02:22+00:00 August 17th, 2017|Physics|

Clothesline pulley A pulley is really a kind of wheel, just as a screw is a kind of inclined plane. But pulleys are so important that people give them their own category. A pulley is a wheel with two raised edges. The raised edges are so that a rope or a string will run along the wheel [...]

Types of lever – Simple machines – Physics

By | 2017-08-17T09:26:03+00:00 August 17th, 2017|Physics|

What kind of lever is a see-saw? All levers fall into one of three types of lever. How can we tell which lever is in which class? Well, a first-class lever is a stick where the fulcrum is in between the weight and the energy moving the weight (your hands, for example). Some [...]

Levers – Simple machines – Physics

By | 2017-08-17T09:06:01+00:00 August 17th, 2017|Physics|

An orangutan child using a stick as a lever A lever is basically just a long stick that you push or pull against a fulcrum - a fixed object - to move something. A lever helps you move something heavy, or make something go fast. The earliest levers developed naturally inside animals' bodies. Whenever [...]

Simple machines – Physics

By | 2017-08-17T09:01:28+00:00 August 17th, 2017|Physics|

An example of a screw, a wedge, a wheel and axle, and a lever Machines are ways to make it easier to do work. Many plants and animals have evolved natural machines like arm muscles (a kind of lever) or teeth (a kind of wedge) or a bacteria's flagellum (a kind of screw). Many animals also make machines out of [...]

Inclined plane – Simple machines – Physics

By | 2017-08-16T23:14:51+00:00 August 16th, 2017|Physics|

Earth ramp to the fortress at Masada (Thanks to www.HolyLandPhotos.org) An inclined plane is any slope or ramp, like a wheelchair ramp or a slide. The ramp makes it easier to lift something heavy, like a rock. Instead of lifting the rock straight up, you can push it a greater distance, but with less force. [...]