# Catapults, Gears and Pulleys For Your Homeschool Science Curriculum

Simple machines always fascinate me and I’m sure they will fascinate you enough to tell your parents or homeschool teacher to add them to your homeschool curriculum. In the following experiments, I am going to show you how to build some simple machines with household articles.

The following homemade simple machine is a kind of a lever that helps lift a ping pong ball and various heavy objects. I will teach you to build it in no time and to make your homeschool curriculum exciting.

Easy Popsicle Catapult: Place five large sized popsicle sticks one above the other and bind them firmly together by winding rubber bands on both ends. Now bind two large-sized popsicle sticks in the same way but only wind the rubber bands around one end. Pull the free ends of the sticks wide apart in the shape of a “V.”

Now insert the stack of five in between the two sticks forming a V and push it towards the rubber band end, widening the angle of the V. Now obtain the intersection with rubber band. Next, place the V on its side so that one arm of the V is resting on the table. On the other arm, glue a cap of a milk jug with the open end up. This cap holds the projectile, which could be a ping pong ball. Just a flick of the catapult’s arm will send the ping pong ball in the air. Have fun!

Gears are wheels having teeth along their rims. These teeth fit into each other so that when force is used to turn one wheel the same force is relayed to the other wheel.

Bottle Cap Gears: Flatten out two bottle caps in such a way that they are round in shape and their edges are nevertheless wavy. Now make holes in the center of both and nail them to a wooden board in such a way that their wavy edges are in contact with each other, forming the teeth of the gears. When you rotate one cap, the other will also rotate, but in the opposite direction. This is a cool example of simple gears.

Some gears have wheels of unequal diameters. In such a case, when the larger wheel turns once the smaller wheel turns many times and consequently magnifies the force.

The pulley and belt combination is used in many machines. The belt helps convey strength from one pulley to the other. Many vehicles use this mechanism to relay strength to all wheels. When pulleys of different sizes are used, torque (driving strength) can be traded for speed and vice versa. The following homeschool curriculum experiment that I have designed will help you see how.

Cool Pulley and Belt Mechanism: Find an old roller skate with the wheels projecting from the sides. The new inline models will not work. Place the skate on its side so that it rests on one set of wheels and the other two wheels are facing upwards. Wind a rubber band over these two wheels. You are using the rubber band as a belt. What happens when you rotate one wheel clockwise? Which way does the other wheel rotate?

Now remove the rubber band from one wheel, keeping it nevertheless wrapped around the other wheel. Give the rubber band a twist so that it looks like an 8 and put it around the wheel. Now rotate one wheel clockwise. Which way does the other wheel turn? I have now given you a fair idea of how belts are used to make pulleys or wheels turn in the desired direction.

Ball Bearing Experiment: Take a clean paint can without the lid. You will see that after removing the lid there is a rim that is grooved. Now place an old heavy book or a similar object on this groove. Try to turn the book. You will notice that the book does not easily turn on the can.

Place some marbles all along the rim and place the same book on the marbles. Now try to turn the book. Is it easier? However there is nevertheless friction between the marbles. How about putting a few drops of cooking oil in the ridge of the rim (this can get messy, so you may use a wooden sheet or a chopping board instead of a book).

Now place the object over the marbles and turn it. Is it easier to turn the book? The above homeschool curriculum experiment will give you an idea about how ball bearings are used in simple machines to reduce friction.
Click the link below to check out the free “Homeschool Parent’s Guide to Teaching Science”, for more great science experiments and activities.

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