Cartesian Ketchup Divers

What you need:

• ketchup/mustard or any other condiment packet
• 20 oz or larger bottle
• water

What to do:

1. Fill the bottle with water
2. Place the condiment packet in the bottle
3. Replace the cap
4. Squeeze the bottle and watch as the packet floats up and down!

What’s the Science?

Squeezing the bottle puts pressure on the water inside. Because the force of squeezing the water in the bottle can’t go anywhere because it is enclosed the force is transmitted to the ketchup packet and it gets pushed down. This force disappears when the squeezing stops and the ketchup packet diver returns to the original position.

Supplemental Materials:

Vincent, D., Cassel, D. & Milligan, J. (2008) Will it float? Science and Children. Vol. 45, No. 6, 36-39.

Standards Alignment:

Ohio, Physical Sciences, 3-5, C

Michigan, Matter and Energy, Middle, IV.1