Students explore a non-Newtonian fluid, polyethylene oxide, nicknamed polyox.
When polyox mixes with water, its oxygen atoms can attach to hydrogen atoms in the water, setting up lots of chains in many directions. Because polyethylene oxide has a lot of oxygen atoms on the chain, there are lots of opportunities for binding. The resulting gel is very thick because its molecules like to stick together, a process called cohesion. Strong cohesion properties can also impact how a fluid flows and in fact, polyox does not flow like other liquids.
When you punch a bucket full of polyox, the stress introduced by the incoming force causes the atoms in the fluid to rearrange such that it behaves like a solid and your hand will not go through. But if you put your hand into the fluid slowly, it will go through the liquid. If you jerk your hand, polyox will behave like a solid and you'll be able to pull all the fluid out of a bucket.
Students will be able to:
- Investigate the properties of a non-Newtonian fluid.
- Describe the properties of a solid and a liquid.
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