A r c h i v e d I n f o r m a t i o n
Oil the hinges of a door and it will stop squeaking. Rub petroleum jelly on lips to prevent them from becoming chapped. These slippery substances are called lubricants. They are very important in modern technology.
What you'll need
4 envelopes unflavored gelatin
Square baking pan
A mixing bowl
Liquid dish detergent
A watch with a second hand
A table knife
Your science journal
What to do
Cars, trucks, airplanes, and machines all have parts that rub against one another. These parts would heat up, wear down, and stop working if we didn't have lubricants. Lubricants reduce the amount of friction between 2 surfaces that move against each other.
- In a mixing bowl, dissolve the 4 envelopes of gelatin in 2 cups of hot tap water.
- Coat the inside of the pan with vegetable oil. Pour the gelatin mixture into the pan and put it in the refrigerator until firm (about 3 to 4 hours).
- Use the knife to cut the gelatin into cubes about 1 x 1 x 1 inch. You should have about 64 cubes.
- Place 15 cubes into a bowl. Place the second bowl about 6 inches (about 15 centimeters) away from the cube bowl.
- When your parent or a friend says "go," start picking up the gelatin cubes one at a time with your thumb and index finger (don't squeeze!). See how many cubes you can transfer to the other bowl in 15 seconds.
Do not eat the gelatin cubes after they have been handled or after they are covered with lubricant.
- Put all the cubes back in the first bowl. Pour 1/4 cup dish detergent over the cubes. Gently mix the detergent and the cubes so that the cubes are well-coated.
- Use the same method as before to transfer as many cubes as possible in 15 seconds.
- Throw away the cubes and detergent and wash and dry both bowls. Put about 15 new cubes into one bowl and pour 1/4 cup water over the cubes, again making sure the cubes are thoroughly coated. See how many cubes you can transfer in 15 seconds.
- Throw away the cubes and water. Put about 15 new cubes into one bowl. Pour 1/4 cup of vegetable oil over the cubes. Make sure they are well coated. See how many cubes you can transfer in 15 seconds.
- With which liquid were you able to transfer the most cubes? With which liquid were you able to transfer the fewest cubes? Which was the best lubricant (the slipperiest)? Which was the worst?
Celery Stalks at Midnight