5 Examples of Physics in Common Events
Physics is a daunting topic for many, with all the math and theories behind it making it seem rather inaccessible. Perhaps if we were to try and bridge it with things we are used to then that could help people understand and perhaps even appreciate it. With that in mind, lets look at some “everyday” events and see the interesting physics involved with them.
Yes, we are starting with wrinkles because often our day starts being surrounded by them in our bed. But nature is full of them, and they are difficult to describe how they form. But research from MIT may have some insight. They were able to create a mathematical formula that shows how wrinkles develop on round surfaces, as opposed to flat ones.
If we have different density layers with a hard one on top followed by a softer one below, then as material from below changes (like if air is sucked out, dehydration occurs, or saturation is reached) then the inflexible outer layer starts to compact in a regular pattern before devolving into a seemingly random assortment that depends on the curvature of the given moment. In fact, a model that takes into account the materials and curvature was developed that could someday give rise to choosing a design we desire (Gwynne).
Now onto food. Take a single piece of spaghetti, hold it at both ends, and try to break it exactly in half. Difficult, no? It wasn’t until 2005 when Ronald Heisser (Cornell University) and Vishal Patil (MIT) cracked the code. You see, no piece of spaghetti is truly straight. Instead, they have a small curvature to them and when we apply stress to the noodle it will break where that curvature is greatest. The resulting oscillations stemming from the break can cause further ones as the noodle loses structural integrity.
But when the noodles were tested in a temperature and humidity controlled environment, scientists found that if we twist the noodle instead a full 360 degrees and then bend it, the fracture was in the middle. That seems to be because the rotating causes the forces to be distributed lengthwise, effectively rendering the stick in equilibrium (Choi).
One of our favorite childhood objects has a lot of amazing things going on for it. Its high elasticity gives it a large coefficient of restitution, or the ability to return to its original shape. No preferred orientation of the balls has a better elasticity to it. In fact, this is partially why they act like a light ray off a mirror: If you hit the ball at an angle to the ground it will bounce off at the same angle but reflected. As the bounce happens, practically no kinetic energy is lost but what is becomes thermal energy, raising the temperature of the ball by about a fourth of a degree Celsius (Shurkin).
I can hear it now: “No way friction can have a complicated piece to it!” I thought so too, since it should be the interacting of two sliding surfaces. Get lots of surface irregularities and it becomes harder to slide, but lubricate appropriately and we slide with ease.
Therefore, it should be interesting to know that friction has a history to it, that prior events impact how friction operates. Researchers from Harvard University found that not only is just 1% of two surfaces in contact at any time and that frictional forces between two objects can decrease if we take a break, implying a memory component. Crazy! (Dooley)
Most of us can do this, but few know why it happens. For many years, the explanation was that fluid in between our knuckles would have cavitation bubbles in them that would lose pressure as we expand the joints, causing them to collapse and make a popping sound. Just one issue: Experiments showed how after knuckles were cracked that bubbles remained. As it turns out, the original model is still valid to a point. Those bubbles do collapse, but only partially to the point that the pressure outside and inside is the same (Lee).
More topics are out there, of course, so check back in every once and a while as I continue to update this article with more findings. If you can think of something I missed, let me know below and I will look more into it. Thanks for reading, and enjoy your day!
- Choi, Charles Q. “Scientists Crack Spaghetti Snapping Mystery.” Insidescience.org. AIP, 16 Aug. 2018. Web. 10 Apr. 2019.
- Dooley, Phil. “Friction is determined by history.” Cosmosmagazine.com. Cosmos. Web. 10 Apr. 2019.
- Gwynne, Peter. “Research Projects Reveal How Wrinkles Form.” Insidescience.org. AIP, 06 Apr. 2015. Web. 10 Apr. 2019.
- Lee, Chris. “Cavitation dilemma resolved in knuckle-cracking model.” Arstechnica.com. Conte Nast., 05 Apr. 2018. Web. 10 Apr. 2019.
- Shurkin, Joel. “Why Physicists Love Super Balls.” Insidescience.org.. AIP, 22 May 2015. Web. 11 Apr. 2019.
© 2020 Leonard Kelley