Praxis: Feel the pressure
By Medicine Hat News on September 16, 2017.
This week, I must confess something. Someone stumped me with an experiment. It was so ingenious; I am just going to have to share it with all of you. It is not only a good practical joke that you could let your unsuspecting victim fidget with for quite some time, or it can be a great learning opportunity about closed systems. *Remember to ask an adult before doing this experiment Materials – mason jar with a two piece snap lid – rubber glove (the thick yellow kind you use for washing dishes) – volunteer Procedure 1. Put your hand in the glove. 2. Does it fit? 3. Is there anything special about the glove? 4. Take the glove and place it in the jar with the fingers pointing down. 5. Take the top of the glove and fold it over the top of the jar. 6. Secure the glove in place with the snap ring only. 7. Try to put your hand in the glove now. 8. What happens? What is going on? Upon closer examination I finally realized this experiment is virtually identical one that I fool people with trying to get them to blow up a balloon in a bottle! Here, you stretched the top of the glove over the rim of the jar. This seals the jar off and nothing can enter or escape the jar any longer. You created a closed system. Your hand will not fit into the glove very easily because the jar is already full. Look at it. No, you say — yes it is. There is something you cannot see — air is also taking up a lot of space. You may be able to force your hand into the glove, but it will be tight and really hard to do. You will be able to feel the pressure squeezing your hand. Teachers please do not forget to book your Hands-on Learning Kits, Scientists in the Classroom presentations and Science Fair 101 Program as soon as possible. Spots are filling up fast! 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. 20-19
