Hobbies And Interests
The Inclined Plane in an Archimedes Screw
The Archimedes screw is a device for shifting water uphill. It is basically a set of channels acting as inclined planes wrapped around a axle in a helix. One end of the axle is dipped into the water, the axle is positioned at an angle to the water and rotated, drawing water up the channels. You can construct these quite simply by wrapping flexible pipes in a helical pattern around a rigid pipe and joining the end of the rigid pipe to a bike wheel to make it turn.
Levers in Catapults
A trebuchet-type catapult is one of the most exciting examples of levers for fifth graders. When a large weight is moved over a short distance at one end of the catapult, the other, longer and lighter end is moved at great speed, tossing the projectile a great distance. There are countless plans for building catapults available on the internet, from small-scale projects that can be accomplished in an hour or two, to much larger undertakings.
Pulleys in Cranes
Cranes use pulleys to allow them to lift and move vast weights. Often, they also use leverage to maintain stability when loaded. Look at examples of modern cranes and note where the pulleys are. Have a go at making your own. Buy or borrow a pulley wheel -- most school physics labs will have one. Tie the pulley over a secure beam or branch and show students how, by increasing the number of loops in the system, the amount of mechanical advantage can be increased.
Simple Machines in the Everyday World
Once students understand the idea of how simple machines confer mechanical advantage, show them how examples of these principles operate in the things they use every day, not just in bigger, more complex machines. Show them how scissors and bicycles use levers and how bottle-cap screws use inclined planes. Get them to track down their own examples.