Homemade Sciencewith Bruce Yeany

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Cartesian Divers: printable worksheets

Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.

Ages 5-7: Draw & tell
Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Cartesian Divers · Ages 5-7

My Diver

Watch your diver go down and up.

1. Draw your diver inside the bottle.

2. I squeeze the bottle. The diver goes...

◯ up◯ down

3. I let go. The diver goes...

◯ up◯ down

4. Draw the air bubble in the diver when you squeeze. Make it big or small?

5. What else could be a diver?

Ages 8-10: Predict, test & record
Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Cartesian Divers · Ages 8-10

Diver Detective

Predict, test and find out what makes the diver sink.

1. Predict: when you squeeze the bottle, the air bubble inside the diver will get...

◯ bigger◯ smaller◯ stay the same

2. Test each one. Write whether the diver sank or stayed up.

TryWhat I didWhat the diver did

3. Does it matter where you squeeze the bottle (top, middle or bottom)?

◯ yes◯ no

4. What happened when the cap was loose?

5. What did you find out about the water inside the diver when it sinks?

6. Why do you think the diver floats back up when you let go?

Ages 11-14: Explain & design your own test
Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Cartesian Divers · Ages 11-14

Pascal, Archimedes and the Diver

Explain the diver with the science and design your own fair test.

1. Use Pascal's principle to explain why squeezing the side of the bottle affects the air bubble inside the diver.

2. Use the words density and buoyant force to explain why the diver sinks.

3. Compared with when it floats, the buoyant force on the diver when it sinks is...

◯ greater◯ smaller◯ the same

4. If the diver hovers halfway down, its weight is...

◯ greater than the buoyant force◯ less than the buoyant force◯ equal to the buoyant force

5. Design a fair test: does the amount of water in the diver change how hard you must squeeze? Change one thing only.

Water in diverSqueeze needed (light / medium / hard)Kept the same

6. Where else is depth controlled by changing the size of an air space?

Answer guide for grown-ups

Homemade Science with Bruce Yeany · Cartesian Divers · Answer guide

Answer guide

Ages 5-7: My Diver

  1. Open answer: look for effort and careful observation.
  2. down
  3. up
  4. Small: the bubble gets smaller when you squeeze.
  5. Any small thing that floats with air inside, like a ketchup packet, a straw or a toy.

Ages 8-10: Diver Detective

  1. smaller
  2. Open answer: look for effort and careful observation.
  3. no
  4. The diver hardly moved; the squeeze pushed water out the top instead of squeezing the bubble.
  5. More water goes into the diver (the water level rises in the tube) and the air bubble gets smaller.
  6. The squeezed air bubble springs back to its full size and pushes the extra water out, so the diver is lighter for its size and floats.

Ages 11-14: Pascal, Archimedes and the Diver

  1. The squeeze raises the pressure in the sealed water, and Pascal's principle says that increase reaches every part of the fluid equally, including the air in the diver, which compresses.
  2. With a smaller bubble, the diver holds more water, so its average density rises above water's. Its weight is now greater than the buoyant force, so it sinks.
  3. smaller
  4. equal to the buoyant force
  5. Open answer: look for effort and careful observation.
  6. Submarine ballast tanks, a fish's swim bladder, a scuba diver's buoyancy vest.