Table of Contents Module 4


lot of force to lift and move something heavy, but it’s much easier to push it up a ramp. It is much harder to move things up steeper ramps, or ramps that go up higher, just as it is harder for people to walk up a bigger or steeper hill.


A lever is a simple machine that consists of a bar that rests on a fulcrum, or a point that does not move. A lever can also help lift up heavy loads. A seesaw is the classic example of a lever. When force is applied to one side and is pushed down, the other side lifts up. Winch handles and tiller extensions are examples of levers on sailboats.


A wheel and axle work together to make a simple machine. Explain that a wheel turns around a rod, called an axle. A wheel and axle can help move things faster or more easily, and also help things turn. Carts, skateboards, roller skates, bikes, and cars all use wheels and axles. Explain that heavy things can be difficult to push across a surface and can require a lot of force. But, if you add wheels to the bottom, it becomes much easier. Wheels and axles can act as fulcrums, as well. A wheelbarrow can lift and carry very heavy items using wheels as rotating fulcrum points. Have children give examples of how wheels and axles make work easier.


A pulley is a simple machine that has a rope or cable that goes over a wheel. A pulley helps people lift things up and change the direction of their force. You pull on a rope to make the load go up. You can also connect pulleys together, creating a combined pulley that requires less than half the force otherwise needed to lift up a load. Clotheslines, flagpoles, and blinds use pulleys.


Help students understand that combining simple machines can also make work easier. Any two or more simple machines put together are known as compound machines. Many machines are compound machines. For example, a crane uses levers, wheels and axles, and many pulleys to lift up heavy objects. Learning about simple machines and forces is a great way to teach the fundamentals of physics and help children understand the world around them. Simple Machines are used on sailboats to reduce the amount of work needed by the sailor and help us move things. There are six simple machines; the most common simple machine found on a sailboat is a pulley. Sailors call pulleys blocks.


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