Praxis: Catching magic in a bottle

By Medicine Hat News on June 23, 2018.

I don’t know about all of you, but the anticipation of summer break is driving us absolutely mad at our house. School will be out in about a week, if you aren’t one of the lucky ones who has already finished. It’s hard to believe another school year is coming to an end. We are frantically planning out our summer camps at Medicine Hat College and wow!, are there ever some exciting offerings for all ages — from Construction and Building for little ones to a Mysterious Magic or Spa Science camp for older children. Don’t worry if you already have a summer packed full of fun, I will be “sneaking” a few of my favourites into my column each week; so keep reading each and every week for some exciting STEM activities to do over the summer break. Let’s get started!

*Remember to ask an adult for help before doing this experiment.

Materials

– 500 mL plastic drinking bottle

– water

– straight drinking straw (not the bendy kind)

– plasticine

– science volunteer

Procedure

1. Rinse the plastic bottle out very well. It should be clean, very clean.

2. Fill the bottle 3/4 full of water.

3. Take a piece of plasticine and shape it around the straw. It should be quite thick.

4. Place a straw in the bottle.

5. Hold the straw off of the bottom of the bottle.

6. Firmly press the plasticine around the mouth of the bottle.

7. Make sure you create a tight seal with the plasticine between the straw and the bottle.

8. Hand the bottle to your volunteer.

9. Ask the volunteer to try to drink through the straw.

10. What is going on?

11. Tell them to suck really hard.

12. What happens?

Explanation

If you created a strong airtight seal with the plasticine, the volunteer should not have been able to suck more than a tiny amount of water through the straw. Ideally, they should not have been able to get anything at all.

The volunteer is unable to drink through the straw because of something called air pressure. In order for the straw to work properly, there needs to be outside air pressure. In a normal situation, when you drink through a straw, the outside air pressure assists the liquid to be forced up the straw. Since you sealed the bottle off with the plasticine, the outside air is unable to get in and push the water up the straw. You are out of luck with this bottle; you had better try another one if you are thirsty!

Patty Rooks is senior scientific consultant at PRAXIS, “Connecting Science To The Community.” Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook.

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