A wheel and axle is an example of a simple machine that transfers and magnifies force. You can easily make wheels and axles from household objects such as cylindrical container lids and pencils, but in order to understand the way a wheel and axle transfer energy it is a good idea to make a pinwheel or windmill. This simple project demonstrates how a force applied to a wheel is magnified in the axle to create a mechanical advantage.
Draw a straight line from the top left corner of the square of the card to the bottom right corner using a pencil and ruler. Draw another straight line from the top right corner to the bottom left corner to create an "X."
Place a 50-cent piece in on the centre of the cross and draw around it.
Punch a hole in the top right corner of each triangular section on the card using a hole punch. Punch a hole through the centre of the circle in the middle of the card using a sharp pencil.
Cut along the diagonal lines from the corners of the card to the edge of the circle in the centre.
Fold the right corner of each triangular section of card down toward the centre one by one so that all the holes are aligned with the one in the centre circle.
Push a drinking straw through the holes so that the card pinwheel rests in the middle of the straw. Tape the pinwheel in place and wrap a thin strip of plasticine around the straw on either side of it to prevent it from sliding along.
Hold your hands out in front of you, palms facing each other, and make a "V" shape with the thumb and forefinger of each hand. Lightly rest the ends of the straw in the "V" shapes and blow gently on the pinwheel to make it spin.
Tape a piece of cotton with a paper clip tied to the end to the drinking straw axle to see how the clip is raised when you blow on the pinwheel.