Monday, March 7, 2016

Liquid Density Experiment

  • 3 clear containers (such as mason jars)
  • 1 large container
  • heavy liquid (like honey, corn syrup, or molasses)
  • water
  • vegetable oil
  • food coloring
  • household items: coins, plastic beads, bottle caps, popcorn, grapes, safety pins...

  • Pour a cup of each liquid into the containers.
  • Use the food coloring to dye the liquids.
  • Guess which liquid will rise to the top when you mix all of them together.
  • Pour all the liquids into one jar and wait for them to separate.
  • Then predict how far each household item will fall inside the container.
  • Add in the household items one by one and see if you guessed correctly!

  • Density is equal to the mass of the substance divided by the volume.
  • When you pour all of the liquids together, liquids with heavier density will sink, while liquids with lighter density will rise to the top.
  • When you add the household items in, the ones with more mass per unit volume will sink lower than the ones with less mass per unit volume.


Wednesday, March 2, 2016

Soap-Powered Model Boat

1. A foam tray (like the kind meat comes in) or a piece of non-corrugated cardboard
2. A tray, bowl, or cookie sheet full of water
3. Liquid dish soap
4. A toothpick

What To Do:
1. Cut the foam tray or cardboard into a boat shape as shown below:
2. A good size seems to be about 2 inches long.
3. Dip the toothpick into the liquid soap and use the toothpick to put soap onto the sides of the notch at the back of the boat.
4. That’s it! Now carefully place the boat onto the surface of the water and watch it scoot across the water for several seconds – you’ve made a soap-powered boat! To demonstrate the boat again, you will need to rinse out the tray to remove any soap from the previous demonstration.
5. Try to answer the following questions while working with this project:
      - Does liquid soap last longer than a solid piece of soap?
      - Does warm water work better than cold water?
      - What materials make the best floating boat?
Displaying Soap Powered Model Boat.JPG

How Does It Work?
Soap is a surfactant – that means that it breaks down the surface tension of water.  As the surface tension is broken up, it creates enough of a force to push the lightweight boat across the surface.