How is physics knowledge used in everyday life?

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We all know the question: why do I need to know this? I have been thinking recently about how to add relevance to my curriculum. What I am struggling to come to grips with is how knowing physics, the topics typically taught in a high school intro course, can be useful in everyday life. I am not looking for everyday examples of physics concepts. I mean real actual examples of using Newton’s laws or momentum in real life purposefully. For example, understanding ratios from math is applied purposefully to compare grocery store prices.

Can you think of a time when you actually used your physics knowledge in everyday life?

Thanks,
Bill
 
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  • #2
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We all know the question: why do I need to know this? I have been thinking recently about how to add relevance to my curriculum.

Can't answer you directly w/r/t Physics, but let me suggest a parallel response:

Many years ago I found myself trying to explain to a student (who likely had no need or interest in the subject) why polynomials were important to her life. I came up with some lame answer--and was never really satisfied with it. Perhaps there's a real answer that I missed, but I wasn't aware of one at the time :smile:.

I later came to the conclusion that I should have focused on this point: people need to learn how to cope when faced with doing things that are difficult... as life tends to present us with these challenges. This is important for emotional growth and confidence-building, of course. But it's also important from the standpoint of increasing someone's awareness that they might be able to do things that they wouldn't have imagined for themselves, and perhaps even like them. And from a technical standpoint, it can lead to developing the skills required for how to approach problems, break them down, etc. The latter two points tend to be dependent on some success with the first :wink:.
 
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  • #3
jack action
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If I drive at 100 km/h, I know that I will reach my destination situated at 200 km from my house in 2 hours. That's a direct application of kinematics, calculations included.
 
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  • #4
jack action, that is the only example I can think of as well. Unfortunately I cannot think of other similar typical uses for the other concepts.
 
  • #5
I feel like I use physics all the time, but it's not the laws or equations, it's the approach to problem solving and critical thinking. It's a sort of checklist when I'm thinking about a situation or trying to reason through simple arguments: 1) What do I know about the situation and what is my relevant prior knowledge, 2) Can I construct a simple model to explain or reason through the situation, 3) Does my model/explanation reduce to known behavior in different limits, 4) Does my model/explanation imply anything that is obviously ridiculous and therefore wrong, 5) What are the additional implications of my model/explanation.

Granted, I am a theoretical physicist.

Regarding application to everyday experience, I guess it's hard to think of something. I never find myself calculating things, as you described. I think physics may be more useful, in this context, for understanding the qualitative behavior of things. I guess as an example, I once had an issue where food-waste was coming up through my shower (coffee grounds, etc.). I don't know anything about plumbing, but I reasoned that the pipe for the kitchen sink must be connected to the pipe for the shower drain. There must have been a blockage below where they meet each other and the sink, in a different room, is at a higher height than the drain (throw the notion of "potential energy" in there if you like). I knew that significant pressure could dislodge the blockage, so I tried filling the kitchen sink with water, then unplugging it to force the blockage away. I didn't want to fill the bath tub because I figured it wouldn't produce as much pressure through a LATERAL section of pipe...anyway, the sink was higher, so obviously the best choice. This strategy was moderately helpful, but we just had our landlord snake the thing in the end. Perhaps not the best example...
 
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  • #6
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I think it depends on what you mean by "use".

I find that I recognize physics in action around me all the time. Moments ago I emptied used tea leaves from the strainer by inverting it and putting the strainer and leaves into motion. I stopped the strainer by hitting it on the edge of the compost bin but the leaves remained in motion and flew into the bin. (I recall making the parallel connection several years ago when stamping my foot to get snow off of it.)

I could argue I use my knowledge of physics to moderate how fast I make turns in my car to prevent the GPS unit from sliding off the dashboard, but is more that physics lets me understand why.

I once heard Garrison Keillor say that education is a matter of learning to love the world better. Learning physics clearly does that for me.
 
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  • #7
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Subconsciously or unknowingly you use physics all the time. Braking for a stop sign. Hammering in a nail. Walking down the street..
 
  • #8
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Can't answer you directly w/r/t Physics, but let me suggest a parallel response:

Many years ago I found myself trying to explain to a student (who likely had no need or interest in the subject) why polynomials were important to her life. I came up with some lame answer--and was never really satisfied with it. Perhaps there's a real answer that I missed, but I wasn't aware of one at the time [emoji2].

I later came to the conclusion that I should have focused on this point: people need to learn how to cope when faced with doing things that are difficult... as life tends to present us with these challenges. This is important for emotional growth and confidence-building, of course. But it's also important from the standpoint of increasing someone's awareness that they might be able to do things that they wouldn't have imagined for themselves, and perhaps even like them. And from a technical standpoint, it can lead to developing the skills required for how to approach problems, break them down, etc. The latter two points tend to be dependent on some success with the first :wink:.
Well I think that what you said is brilliant and on point!
 
  • #9
Aufbauwerk 2045
I majored in physics at university, so of course my high school physics was vital, but I will try to answer more generally.

As a programmer, I have worked on a video game. My knowledge of some physics made it easy for me to understand game physics, which is an important topic if you are trying to make your game realistic. In addition, some of the mathematics I learned specifically for physics made it easy for me to learn computer graphics. For example, in CG we use vectors and matrices. This is one of those math topics we need for physics.

I also did some work in electronics. At university I studied electronics as part of my physics major. Naturally this helped me in the real world job. In general, I think it would be very useful for everyone to know enough about electricity and electronics to be able to understand auto electronics or home appliance electronics.

Our everyday life does include our job. If I was a high-school physics teacher, I would emphasize the importance of basic physics in studying other subjects, which would be preparation for many types of work. Some I can think of just on the spur of the moment are: medical technology, mechanical engineering, construction, plumbing, automobile mechanics, aircraft mechanics, boat mechanics, lighting technology, air conditioning and heating, police forensics, wireless technology, cable technology, consumer appliances, and no doubt many more.

I saw an interview tonight with someone in the nuclear industry who says there will be a growing demand for jobs in that field. This reminds me also of solar power, wind power, and perhaps other technologies. Consider also robots and drones. For those who are so inclined, how about a job in the military or the space program, involving technology? You won't get far without at least a basic knowledge of physics. Anything you learn in high school will make your advanced study that much easier.

I would point out that there are other roads to a good job besides a four-year university, and in many fields a knowledge of basic physics is essential. I would explain the prospect of a solid high-paying job that may not require a four-year degree. We have another story today that the government is working with industry to train more students in various technical areas, because we will need the workers.

As far as just general knowledge of the world around us, I think all basic science is important. But if I was trying to motivate students, I would focus on practical benefits, namely a good job!
 
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  • #10
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jack action, that is the only example I can think of as well. Unfortunately I cannot think of other similar typical uses for the other concepts.

Er... building structures all work because someone knew about classical mechanics such as Newton's laws.

The banking of curves when you get onto a ramp is described to Newton's laws.

You slip and fall on slippery surfaces, and I can explain that with Newton's laws.

Going beyond mechanics, each time you use your microwave, you are using knowledge from physics. Your electronics are downright physics application.

The applications of physics in our everyday world is too many to describe!

Pick up the text "College Physics" by Giambattista, Richardson, and Richardson". This is a General Physics text for courses aimed at Life Science, Biology, and Pre-Med students. Every single physics topic covered in the text are accompanied with biology and bio-medical applications.

Edit: BTW, I should have included this article by Chad Orzel "What Has Quantum Mechanics Ever Done For Us?" This would have answered several other threads that asked for the application of QM.

Zz.
 
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  • #11
jack action
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Here's another example, maybe more qualitative, but very important nonetheless.

When I was younger, I used to hit ketchup bottles on the bottom to help the ketchup coming out. That is the way we see everywhere, the way that looks 'cool'. I also learned about the 'other' way, where you hit your hand with the arm holding the ketchup bottle instead. I thought I looked stupid doing that and wasn't even sure what difference it would make. I often used the 'cool' way on fear to be judged, even if it didn't work very well; I just thought I was unlucky and had a stubborn bottle.

That all changed when I learned about physics. I realized why it should work better while hitting your arm and why you are actually not helping yourself by hitting the bottom of the bottle. Now, I know that the 'weird' way is actually the 'smart' way. I 'm proud of using it and even if someone would laugh at me for using it, I can now explain with confidence why it is the right way, something I could've never done before learning physics.
 
  • #12
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Think of the tricks used to perform the simple task of twisting the lid off a jar. If your hands are wet, you use a towel to increase the coefficient of static friction. If that doesn't work, you hold the lid of the jar under hot running water for several minutes. The metal lid has a higher coefficient of thermal expansion than the glass mouth of the jar and the seal cracks open (it doesn't take much of a differential expansion to do the trick). Also, a jar opening tool provides a longer lever arm so you get more torque for the same force.
 
  • #13
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No sign of actually answering the topic question, after reading through the post #12. Most people do not USE Physics in everyday life, except maybe some engineers and a few programmers. It is really the other way around: Physics uses YOU in everyday life.
 
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jack action
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Most people do not USE Physics in everyday life, except maybe some engineers and a few programmers.
The reason they don't use it is because they don't know it or don't understand it. If they did - just like engineers and programmers - they would. I shared a personal anecdote related to this on another thread about a year ago:
I remember when one of my friend was renovating his house. He had plan to open up a straight stairway going to the basemen that had a door opening into a hallway. He intended to remove the door and make a simple opening in the wall between the staircase and the living room to let some natural light brighten the stairway.

I suggested to him to transform it into a winder staircase that would end up into the living room instead of the hallway. He told me: «That would be ideal, but we can't rebuild the staircase, that's too hard.» After discussing with him for a little bit, telling him I saw this as only an exercise in geometry, he asks me if I would do the plans for him; A challenge that I accepted. This stairway is probably the best part of his renovated house.

The point is that for someone like him, if asked to build a stairway, his answer is simply: «It's impossible.» He then forget about such plans and move on to the next solution that requires simpler knowledge. Then when he's asked if he uses geometry, he responds: «I never used that! I don't know why they teach that in school!»
 
  • #15
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No sign of actually answering the topic question, after reading through the post #12. Most people do not USE Physics in everyday life, except maybe some engineers and a few programmers. It is really the other way around: Physics uses YOU in everyday life.

Okay, but in fairness... there is a slight difference between the thread topic ("How is physics knowledge used in everyday life?") and the lead-in sentence:
We all know the question: why do I need to know this?
So some of us strayed beyond the thread topic to examine why and to whom does it matter.

[Edit]: And actually, note that the topic asks how knowledge of physics is used.... This is even a more restrictive requirement.
 
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  • #16
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We all know the question: why do I need to know this? I have been thinking recently about how to add relevance to my curriculum. What I am struggling to come to grips with is how knowing physics, the topics typically taught in a high school intro course, can be useful in everyday life.

May I ask what is really driving the question, then? I tend to agree with the overall point made by @symbolipoint and @jack action that students who are highly technically inclined would be the ones most likely to intentionally--i.e. consciously--use Physics in their lives. But I would argue that they would likely do that anyway on their own. My interpretation (right or wrong) from your question was that you were trying to reach those for whom this wouldn't be the case.
 
  • #17
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No sign of actually answering the topic question, after reading through the post #12. Most people do not USE Physics in everyday life.
Right. I think the honest answer to the question Why do I need to know this? is "You don't."

Okay, but in fairness... there is a slight difference between the thread topic ("How is physics knowledge used in everyday life?") and the lead-in sentence.
I think it's misguided to justify the learning physics using practical applications. There's an assumption here that unless knowledge is directly applicable, it's not worth the effort of learning it. With that criterion, you could argue that almost everything you study in school is a waste of time.

I think a good smart-ass response to someone asking "Why do I need to know this?" would be "Why do you want to remain ignorant?" Being exposed to our current understanding of how the universe works and learning how to analyze and solve problems can only help one evaluate new situations and make more-informed decisions.

So, sure, you can get by without knowing physics, math, and science in general. But you'd be better off if you did have at least some understanding of what we've learned.
 
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  • #18
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I think it's misguided to justify the learning physics using practical applications. There's an assumption here that unless knowledge is directly applicable, it's not worth the effort of learning it. With that criterion, you could argue that almost everything you study in school is a waste of time.
I agree; that's kind of what I was driving at in post #2.

My later responses were meant to:
  • Explain why it was easy to wander off the topic.
  • Ask which was the thread really about: the practical implications of the official "topic", or the less defined theme suggested by "why do I need to know this?".
I think a good smart-ass response to someone asking "Why do I need to know this?" would be "Why do you want to remain ignorant?" Being exposed to our current understanding of how the universe works and learning how to analyze and solve problems can only help one evaluate new situations and make more-informed decisions.

Sure. Again, I agree in principle. But isn't that a little harsh? Consider the context: high school classes. We're not talking about graduate students or even college students. Some students know that in 6 months they are going to begin a career as hairdressers, others know they are college-bound, others have no idea what they're going to do. It's not a homogeneous group of techies.

The student I mentioned in that story above was in a class--one of several--that many students were taking for the 3rd time. Why? Because some genius decided that it was mandatory for all students to take higher level classes than they previously had been--so we could "compete with the Japanese". Should we require all high school students to take Physics III too? We need to be reasonable about this.
 
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  • #19
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We all know the question: why do I need to know this? I have been thinking recently about how to add relevance to my curriculum. What I am struggling to come to grips with is how knowing physics, the topics typically taught in a high school intro course, can be useful in everyday life. I am not looking for everyday examples of physics concepts. I mean real actual examples of using Newton’s laws or momentum in real life purposefully. For example, understanding ratios from math is applied purposefully to compare grocery store prices.

Can you think of a time when you actually used your physics knowledge in everyday life?

Thanks,
Bill

There are many people who know nothing of physics and manage everyday life without problems. They can drive a car, make a cup of coffee, play sports etc. without any direct knowledge of the underlying physics. Therefore, logically, a knowledge of physics is not necessary for everyday life.
 
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  • #20
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I think it is disingenuous to promote physics because of its everyday utility. Studies have shown that students have preconceived concepts of realities the explanations of which are usually flawed. Even after a course in physics many students who "learned" the correct explanation for the course will revert back to the preconceptions after finishing. Given that the opportunities to use physics or think about physics in one daily life is limited to remote situations and one cannot be too optimistic in thinking that the correct explanation will be accurately recalled.

I believe that physics like other subjects must be promoted for its intellectural enrichment in particular study of relationships for the development of logical approaches to thinking. It should be offered up as a choice and honestly promoted. Most people have taken multiple courses in history, social sciences, philosophy and literature and yet do not vote in elections, read classics or even good contemprotary literature or care that much of their own well being let alone of their fellow man.
 
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  • #21
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The better question for the student might be “Why should I value learning physics?”

For me, part of that answer is what I noted above: it lets me love the world better. (In less personal terms, it lets me find interest in the world around me. I am always figuring out what is going on around me, thinking through things most people would never notice.)

Another thing I value about learning and understanding physics (and science in general) is that it makes me harder to fool. When I hear a claim that apparently violates natural laws, I am able to be pretty confident that I should be skeptical. I similarly recognize claims as suspect because of issues of scale or magnitude.

Physics also gives me the skills to analyze with care, precision and confidence. It strengthens my ability in nearly all things to reason rationally from specific principles.

In taking with the hypothetical student it might be interesting to ask, ““What do you value about learning guitar (or soccer or something else the student connects to)?

Wbadersonjr said the question was related to reevaluating curriculum. For my high school classes I like to ask for any given element, “What do I expect the student to remember about this six months or a year from now?” Articulating what I expect to be retained helps me frame discussions with students about the value of his or her efforts.
 
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  • #22
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Well I think that what you said is brilliant and on point!

I hesitated, but I'm gonna say thanks, and take the money and run. :blushing:

(Just don't put it to a vote.)
 
  • #23
I am a rather bad case for answering this as my work is mainly focused on designing educational scenarios on STEM and doing teacher training. So I do Physics more or less most of my time :-p
To draw the students' attention to Physics I try to find something that intrigues them and then forge connectiona with Physics. This is more or less the reverse approach from what we discuss and applies mainly in project based learning.
So, you could design a semester long project on earthquakes for example and in this framework teach:
- oscillations (to finally understand how does a seismometer work?)
- waves (to finally understand characteristics of seismic waves)
- logarithms (for math teachers, in order students to understand what magnitude is and how it relates to earthquake radiated energy)
Other..

Therefore the idea would be to find an intriguing project that aggregates as many parts of the curriculum as possible and have the students want to learn new physics to be able to carrybout the project.
 
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  • #24
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There are many people who know nothing of physics and manage everyday life without problems. They can drive a car, make a cup of coffee, play sports etc. without any direct knowledge of the underlying physics. Therefore, logically, a knowledge of physics is not necessary for everyday life.

- A couple years ago, I easily drove somebody's car out of a ditch (black ice) by making sure that the CG was sufficiently on the safe side of the balance point. The whole time behind the wheel, my inner ear was screaming at me we were going to tip over.

- A simple acknowledgement of momentum increasing exponentially with speed could have kept her out of the ditch in the first place.



- McDonald's might have something to say about how much latent heat is in a hot cup of coffee.

- There's a company coming out with a phase-change coffee mug which I'm going to purchase and enjoy because I know it isn't hokum. Win-win.

- Don't get me started on Arctic ice, which I can't do anything about, but will definitely vote for a politician who recognizes the phase change and albedo maths.




- Kinesiologists attaching ping pong balls to athlete's joints have been able to make more efficient athletes.



All of the above are "mind over matter". The woman didn't have to call an expensive tow truck, McDonald's paid out millions in a lawsuit, and you can improve your golf swing if you know a kinesiologist.

Everyday applications of physics *principles*, not just muscle-memory and watching YouTube Darwin awards.
 
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  • #25
BillTre
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Any informed use of photographic technique (non-artistic aspects) will involve at least a non-quantitative use of physics.
In some cases calculations can be done.
Certainly mathematical trade-offs between light intensity, aperture size and shutter speed are well know even among those who don't understand them.
 
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  • #26
Can you think of a time when you actually used your physics knowledge in everyday life?
Some good examples of physics used in everyday life can be seen in various career fields, from pilots to cops and firefighters.

Personally, I used physics in everything from accident investigation to other investigations (blood spatter analysis comes to mind). I also used physics in firefighting and investigations. Firefighters who aren't aware of the weight of water while in a high rise building can cause quite a problem, and the engineer supplying the firefighters needs to know hydraulics calculations to ensure the firefighters get the requisite pressures and volume of water to effectively do their job in a high rise.

Knowledge of physics and thermodynamics is important when dealing with different type structures so one is knowledgeable about when to evacuate a building before a collapse.

A lot of physics in certain professional fields (like above) won't be taught in a formal physics class so much as informal classes specific to the need of the profession. You learn hydraulics as an Engineer on a fire truck, and you learn the important parts of what you absolutely need to know, but you don't always need to take college level maths and degree programs for the position: you learn what you need.

Some professions require a more formal education (forensic scientists), but you don't need a physics degree to be an investigator.

Some links to peruse: http://firetrainingtoolbox.com/hydraulics.pdf?lbisphpreq=1
https://quizlet.com/12536831/fire-fighting-hydraulic-formulas-flash-cards/
https://atu587.org/sites/default/files/Traffic Accident Reconstruction.pdf
https://ndaa.org/pdf/crash_reconstruction_basics.pdf
https://www.airlinepilotforums.com/flight-schools-training/19291-aviation-math-formulas.html
https://michael-szczepanski.squarespace.com/s/Math-for-pilots.doc
http://www.iafsm.org/Resources/webinar1/Harald_Krause_Presentation.pdf

Enoy, and I hope that helped.
 
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  • #27
russ_watters
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We all know the question: why do I need to know this? I have been thinking recently about how to add relevance to my curriculum. What I am struggling to come to grips with is how knowing physics, the topics typically taught in a high school intro course, can be useful in everyday life. I am not looking for everyday examples of physics concepts. I mean real actual examples of using Newton’s laws or momentum in real life purposefully. For example, understanding ratios from math is applied purposefully to compare grocery store prices.

Can you think of a time when you actually used your physics knowledge in everyday life?

Thanks,
Bill
Recently, my best friend's wife posted on facebook asking if anyone knew of a good plumber, willing to work on a Sunday, for an emergency: a clogged sink.

So to me the question of whether you will ever use f=ma if you aren't going to be a physicsist or an engineer is really the wrong question. The real question is whether you want to be that guy, who needs a plumber to fix a clogged sink, or if you want to be the guy who knows or can figure out how things work. Honestly, there are times it feels like a superpower.

Full disclosure: when I installed their video doorbell for them, she watched/helped/asked
 
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  • #28
russ_watters
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- A couple years ago, I easily drove somebody's car out of a ditch (black ice) by making sure that the CG was sufficiently on the safe side of the balance point. The whole time behind the wheel, my inner ear was screaming at me we were going to tip over.

- A simple acknowledgement of momentum increasing exponentially with speed could have kept her out of the ditch in the first place.
This is actually a great one. You can teach a person how to drive in certain situations, but if they already know about momentum and static vs kinetic friction, you won't have to.

Last winter, I was going up a hill on the way to work in my front-wheel drive sedan, which I consider terrible in snow. In front of me was an also presumably front wheel drive pickup truck (why does such an abomination exist?), with the driver revving the engine and spinning the wheels. He slowed and slid sideways off the road (gently came to rest against a on the shoulder curb). I briefly considered stopping to explain high school physics to him, but -- momentum!

Most of the examples I'm seeing here are overly specialized. I'm constantly re-engineering the world around me, but I think that's beyond the scope of what a non-STEM might get out of high school physics.
 
  • #29
hmmm27
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This is actually a great one. You can teach a person how to drive in certain situations, but if they already know about momentum and static vs kinetic friction, you won't have to.

In my case, sense-of-balance - geared towards keeping my relatively narrow-stance body upright - said the wider-tracked car was going to tip over sideways, when in fact it wasn't.

Last winter, I was going up a hill on the way to work in my front-wheel drive sedan, which I consider terrible in snow. In front of me was an also presumably front wheel drive pickup truck (why does such an abomination exist?), with the driver revving the engine and spinning the wheels. He slowed and slid sideways off the road (gently came to rest against a on the shoulder curb). I briefly considered stopping to explain high school physics to him, but -- momentum!

I don't think FWD (exclusive) pickups exist ; the closest would the the AWD Honda. Mine's RWD : I find the handling tradeoffs reasonable (and FWD aquaplaning scares the crap out of me), but winter tires are a must.

My point with momentum was it's not intuitive that if you decrease your speed by 1/3, you more than double the steering/braking traction (or other imprecise words to that effect).

I don't recall how she got herself into trouble (if she even said), but from the tireprints in the snow on one side of the road and the skidmarks on the other she'd come up the hill onto the flat, hit some ice, then gone shooting off through oncoming traffic, through a ditch, and halfway up an embankment. I love the first snowfall of the season : it's so entertaining.:rolleyes:
 
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  • #30
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- A couple years ago, I easily drove somebody's car out of a ditch (black ice) by making sure that the CG was sufficiently on the safe side of the balance point. The whole time behind the wheel, my inner ear was screaming at me we were going to tip over.

I think you may be confusing being a skilful driver with having a knowldege of physics. For example, a few years ago my car was blocked in by a parked motorbike. I couldn't see any way to get it out. But, there was someone there who was a van driver: he reversed my car out no problem. That sort of thing doesn't boil down to a knowldege of physics. Even if I went on to get a PhD in physics, I'd still not be able to reverse my car skilfully or get it out of a ditch!

That's one of the jokes in the Big Bang Theory. Sheldon thinks he knows how everything works, but he's never learned to drive a car. His expert knowledge of physics is contrasted by his helplessness and ineptitute in everyday life.
 
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  • #31
PeroK
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Last winter, I was going up a hill on the way to work in my front-wheel drive sedan, which I consider terrible in snow. In front of me was an also presumably front wheel drive pickup truck (why does such an abomination exist?), with the driver revving the engine and spinning the wheels. He slowed and slid sideways off the road (gently came to rest against a on the shoulder curb). I briefly considered stopping to explain high school physics to him, but -- momentum!

That might have been me! I hate driving in the snow.
 
  • #32
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Speaking of driving in the snow, this happened to a colleague physicist. He was entering an exit ramp under extremely slippery conditions. The ramp turn was tighter than usual, but banked. He noticed several abandoned cars off the road that had slid off sideways down the inclined ramp. So he sped up to about 35 mph, which he guessed to be the speed of turning on a frictionless incline, and negotiated the turn without problem.

Most people slow down under icy conditions. That's prudent, but there are instances, e.g. going uphill, when there is such a thing as going too slow as @russ_watters described. I think it has to do with stick-slip behavior near the threshold for slipping. When you "stick" you want to build up enough momentum to carry you through the next "slip" to the next "stick". The time-averaged momentum gained during the stick events must be greater than or equal to the time-averaged momentum lost during the slip events. At least that's how I explained it to myself.
 
  • #33
I have a fun example I remember from high school physics involving inertial physics associated with ripping off the desired amount of toilet paper from the roll. First you slowly pull the tissue with hopefully less force than will break the perforated sheets and enough force to get the roll rolling, extending the tissue to the desired length. Once the desired length is reached, stop pulling paper for a moment and let the roll come to a stop. Then a quick tug will break the tissue at the perforation before the force overcomes the inertia to start the paper rolling again. Well selected angles of force application also help with the desired outcome of stretching vs breaking the tissue at the desired perforation location.

I could probably explain it better with physics if I tried, but what could be a more everyday application of physics than taking a crap and wiping your butt?
 
  • #34
Swingsets, hammocks and metronomes are good for pendulum motion examples for kids between to describe relationships periods, length and moment. Musical instruments vary the musical pitch buy opening and closing holes or changing the length of airflow or the length of a string vibration, resulting in different wavelengths amplifying basic vibrations to a desired musical pitch (each instrument is a little different how it does this to produce different sounds). Other playground equipment can be used although I dont think merry-go-arounds and teeter totters are as popular at public parks as they used to be. Swimming at the pool - buoyancy, weight, drag, fluid dynamics at work. Flushing the toilet to look at gravity, Coriolis effect, fluid and dynamics. Adding Ice to your soft drink to cool it down is an application of thermodynamics. You can stretch a rubber band over your upper lip and feel the thermodynamic cycle happening from entropy - when the band stretches, it gets warmer. You can twist the rubber band to store energy to turn a propeller on a paper airplane, for an example. Experiment with the different designs for paper airplanes, and learn to fold paper so that the aerodynamic center is just at the right location with respect to the center of gravity to see what flies the longest. One time I saw diffraction of light from drops of water on a fence as ice melted, the drops changed color from red to violet as the ice melted and the drops formed and dripped off.
 
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  • #35
hmmm27
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Speaking of driving in the snow, this happened to a colleague physicist. He was entering an exit ramp under extremely slippery conditions. The ramp turn was tighter than usual, but banked. He noticed several abandoned cars off the road that had slid off sideways down the inclined ramp. So he sped up to about 35 mph, which he guessed to be the speed of turning on a frictionless incline, and negotiated the turn without problem.

Some quick thinking, there. I wonder if there's a standard convention for road camber vs posted speed.

Most people slow down under icy conditions. That's prudent, but there are instances, e.g. going uphill, when there is such a thing as going too slow as @russ_watters described. I think it has to do with stick-slip behavior near the threshold for slipping.

In winter, I'm occasionally that guy, on a steep, icy hill : sometimes circumstances mitigate a proper run-up.
 

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