How to Make a Balance Scale With Recycled Materials

A balance scale is a simple and surprisingly accurate way to compare the weight of two things. It works just like a see-saw. If objects of equal weight are added to either side of a lever the same distance from the fulcrum, they will balance perfectly. Otherwise, the heavier one will pull its end down.

Things You'll Need

• Soda bottles Scissors Board Hammer Nail Dirt Glue Tape

Instructions

1. Get a thin board, about 2 inches wide and 1 to 2 feet long. Find the center of gravity by balancing it on your finger. Hammer a long nail straight through the center of it.

2. Cut off the bottoms of two soda bottles of equal size. You can cut off a small section of the bottom or a large one, as long as you cut off an equal piece from each bottle.

3. Attach the bottle bottoms to each end of the wooden board so that both are facing up. You can use tape or glue, or simply nail each to the board.

4. Cut the top off of a 2-liter bottle. Then, cut two grooves into it for the nail to rest in. Put some dirt or rocks in the bottom of the bottle to weigh it down and make it more stable.

5. Rest the nail in the grooves so that the bottle bottoms are facing up, and observe the scale. If it tilts to one side, add some weight to the other until it balances out. You can use small pieces of tape or drops of glue to equalize the weight. Once it equalizes, you can use it as a balance scale.

Tips & Warnings

• If you buy standard gram weights, you can use your balance to determine the actual weight of something.