Concerns the application of the laws of physics to analyze common situations encountered in everyday life.

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How can Magnets be used to pick up pieces of metal when the force from a magnetic field does no work?

I learned that the force from magnetic fields does no work. However I was wondering how magnets can be used to pick up pieces of metal like small paperclips and stuff. I also was wondering how magnets ...
129
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7answers
18k views

Does Earth really have two high-tide bulges on opposite sides?

The bit that makes sense – tidal forces My physics teacher explained that most tidal effect is caused by the Moon rotating around the Earth, and some also by the Sun. They said that in the Earth and ...
73
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5answers
11k views

Why wet is dark?

When something gets wet, it usually appears darker. This can be observed with soil, sand, cloth, paper, concrete, bricks ... What is the reason for this? How does water soaking into the material ...
22
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4answers
4k views

Why does a cork float to the side of a glass?

What is this physical phenomenon and when it's happen ? Please take a look at this picture: Notice: This is a cork ball attracted to sides of a glass of water
35
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2answers
12k views

Why is boiling water loud, then quiet?

Water in my electric kettle makes the most noise sixty to ninety seconds before the water comes to a full boil. I have been fooled many times by the noisy kettle, only to discover that the water was ...
8
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7answers
2k views

Is electricity instantaneous?

My question is basically what exactly is electricity? I've simply been told before that it's a flow of electrons, but this seems too basic and doesn't show that electricity is instant. What I mean is ...
291
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4answers
43k views

Can I compute the mass of a coin based on the sound of its fall?

Other day, I bumped my bookshelf and a coin fell down. This gave me an idea. Is it possible to compute the mass of a coin, based on the sound emitted when it falls? I think that there should be a ...
125
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6answers
13k views

Why do shadows from the sun join each other when near enough?

I was laying on my bed, reading a book when the sun shone through the windows on my left. I happened to look at the wall on my right and noticed this very strange effect. The shadow of my elbow, when ...
19
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8answers
3k views

What's the difference between running up a hill and running up an inclined treadmill?

Clearly there will be differences like air resistance; I'm not interested in that. It seems like you're working against gravity when you're actually running in a way that you're not if you're on a ...
2
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4answers
854 views

How does buoyancy work?

I realised, reading another Phys.SE question about balloons moving forwards in an accelerating car that I don't really understand how buoyancy works. Particularly concerning, for a SCUBA diver. The ...
7
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1answer
937 views

Why do wheels appear to revolve opposite to the direction they are rotating?

When viewing cars that are driving along side of us, sometimes their wheels appear to be turning backwards even though they are traveling in the same direction as our car. Why do they look that way?
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1answer
280 views

Increase in cloth's mass

When we iron our clothes does the mass of the cloth increase, since energy transformation and transfer happens, Einstein's energy mass relation comes to action and causes increase in mass. Am I right ...
81
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11answers
12k views

Why is filling a balloon from your mouth much harder initially?

Why is it that when you first fill up a balloon, it's hard to get air through, but after inflating it a bit, it becomes much easier to further inflate the balloon?
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1answer
7k views

Why do earphone wires always get tangled up in pocket?

What is the reason? Is it caused by their narrow shape, the soft material, walking vibration or something else?
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10answers
24k views

Does car tire pressure change with weight of car load?

Does tire pressure measured by a meter on tire gauge change with load? (I am not interested in pressure produced by car tires onto the road). Car spec usually says "inflate to 220kPa normal load, ...
15
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2answers
2k views

Why does one get an illusion as moon following him?

When you run or ride bike at night if you observe the moon you feel like he moves along with you as the same speed you are going. Why?
29
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6answers
3k views

Canonical everyday-life example of a technology that could not work without humans mastering QM in analogy to the application of GR in GPS?

The GPS is a very handy example in explaining to a broad audience why it is useful for humanity to know the laws of general relativity. It nicely bridges the abstract theory with daily life ...
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4answers
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Do low frequency sounds really carry longer distances?

It is a common belief that low frequencies travel longer distances. Indeed, the bass is really what you hear when the neighbor plays his HiFi loud (Woom Woom). Try asking people around, a lot of them ...
12
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4answers
5k views

What happens when we cut objects?

What is the role of the molecular bonds in the process of cutting something? What is the role of the Pauli exclusion principle, responsible for the "hardness" of matter? Moreover, is all the energy ...
102
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24answers
15k views

How can you weigh your own head in an accurate way?

I read some methods but they're not accurate. They use the Archimedes principle and they assume uniform body density which of course is far from true. Others are silly like this one: Take a knife ...
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3answers
5k views

Why do the big nuts always remain at top? The Brazil-nut Effect

Most of the time when I mixed different nuts in a bowl, I observed that the big Brazil nuts were always on top while the small peanuts settled near the base. No matter how you take it, if the big nuts ...
20
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3answers
7k views

Why is there more steam after a pot of water *stops* boiling?

I have a pot of vigorously boiling water on a gas stove. There's some steam, but not alot. When I turn off the gas, the boiling immediately subsides, and a huge waft of steam comes out. This is ...
6
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1answer
587 views

Height of Water 'Splashing'

Suppose from a height $H$, I throw a ball of mass $M$ and radius $R$ with initial velocity $u$ into a pool of depth $x$ having a liquid with density $\rho$ and coefficient of viscosity $\eta$. ...
24
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3answers
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Why does the moon sometimes appear giant and a orange red color near the horizon?

I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
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2answers
1k views

Why don't we see solar and lunar eclipses often?

Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Earth during the evening ( and as far as I know if this happens during the day, you'll get to see a ...
7
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1answer
324 views

What pressure or tension occurs in a glass jar when I pour boiling water inside?

Sometimes it happens that when you pour a boiling water into a glass jar, it cracks. Since glass is very hard material and resilient to pressure, the tension must be very high. Is it possible to ...
26
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5answers
3k views

Where does deleted information go?

I've heard that, in classical and quantum mechanics, the law of conservation of information holds. I always wonder where my deleted files and folders have gone on my computer. It must be somewhere I ...
24
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7answers
12k views

Why Won't a Tight Cable Ever Be Fully Straight? [duplicate]

I posted this picture of someone on a zipline on Facebook. One of my friends saw it and asked this question, so he could try to calculate the speed at which someone on the zipline would be going ...
45
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6answers
46k views

Why do power lines buzz?

When near high tension power lines, particularly after a good rain, the lines themselves emit a buzzing noise. A similar noise can be heard coming out of the electric meters attached to my apartment. ...
31
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1answer
10k views

Why does paper become translucent when smeared with oil but not (so much) with water?

When I smear oil onto a scrap of paper and rub it in, the paper becomes quite translucent; but when I attempt the same with water it doesn't as much. Why?
17
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2answers
2k views

Why is paper more frangible when it is wet?

My four-year-old daughter asked me why paper tends to fall apart when wet, and I wasn't sure. I speculated that the water lubricates the paper fibers so that they can untangle and separate more ...
15
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4answers
6k views

Why do I always hear remote train horn at night?

This is definitely not an illusion, as many people have the same experience. I have usually lived in places miles away from train stations, which makes it unlikely to hear any train horns during the ...
12
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2answers
1k views

Why does sunset over a body of water cause a path of light stretching towards the horizon?

Have you ever notice the sunset's image in the sea? It's like long light path to the end of the horizon! I've attached a sample of this: How can we explain this? I know that it can happen even in ...
5
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4answers
16k views

Does humidity make winter air feel colder?

I sometimes hear stories where people compare their feelings in winter in different places in the world. It goes like in city X the temperature was the same as in city Y, but the humidity made me ...
3
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2answers
3k views

Relating milliampere-hours to watt-hours for batteries

I've seen many batteries that are measured in milliampere hours (mAh), while others are measured in watt hours (wh). How can I convert them between each other so that I can actually compare them? It's ...
2
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2answers
3k views

Is squared motor gearbox ratio proportional to inertia ratio?

I read an interesting article http://m.machinedesign.com/news/motor-sizing-made-easy It is very interesting, but I can not follow the 2nd last paragraph. I don't understand why it is true. ...
0
votes
2answers
627 views

Observer looking out through the window of a train [duplicate]

When travelling by a train, it seems that the nearby objects move in the opposite direction(which I can explain) but the distant objects appear stationary. I can't explain this. By the concept of ...
43
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5answers
15k views

How effective is speeding?

At a simple level, speeding in a car attempts to minimize the time required to travel a distance by utilizing the basic relationship: $$d=st$$ So for a given distance, time should be inversely ...
46
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17answers
5k views

Quantum mechanics and everyday nature

Is there a phenomenon visible to the naked eye that requires quantum mechanics to be satisfactorily explained? I am looking for a sort of quantic Newtonian apple.
64
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8answers
76k views

Why does a remote car key work when held to your head/body?

I was trying to unlock my car with a keyfob, but I was out of range. A friend of mine said that I have to hold the transmitter next to my head. It worked, so I tried the following later that day: ...
57
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2answers
7k views

Why does dry spaghetti break into three pieces as opposed to only two?

You can try it with your own uncooked spaghetti if you want; it almost always breaks into three when you snap it. I am asking for a good physical theory on why this is along with evidence to back it ...
23
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5answers
6k views

Why are a motorcycle's front brakes more effective than back?

I've noticed that when I apply the front brakes on my bike it stops quite quickly. If I apply the back brakes at the same speed, it skids rather than stopping quickly. Why?
12
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4answers
32k views

Why does a ball bounce lower?

If a ball hits the floor after an acceleration then why does it bounces lower? I mean the Energy is passed to the floor then why does the floor give back less Energy?
0
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1answer
543 views

Why do we observe opposite motion of trees (nearer) and trees (distant) when seen from a moving frame? [duplicate]

If you are in a moving train or in a bus, what you observe is that the trees which are nearer to you move opposite to the direction of your motion. But the trees which are very far away from you, ...
8
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1answer
2k views

How do candles and wicks work?

The wick of my tea candle was buried in wax. So I lit a piece of paper and stuck it in the wax. Now the wax is burning off the paper, as if that were the wick. The wax itself wouldn't light on ...
5
votes
3answers
5k views

Why is moonlight less colourful than yellow light?

Just what the title states; and this isn't an original question: On full-moon, moonlight is almost as bright as mid-dawn; yet there is hardly any colour visible. This is not the case with sunlight. ...
4
votes
3answers
19k views

Why do we use kilograms instead of newtons to measure weight in everyday life?

What was the reason to use kilograms to measure weight (e.g. body weight, market vegetables etc.) instead of using newtons?
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vote
2answers
307 views

Why do corn flakes clump together in milk when stirred? [duplicate]

The Cheerios Effect is the name the scientific community has given to this phenomenon. When cornflakes or oats are mixed with milk and stirred, they tend to clump together. Why does this happen? Can ...
1
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1answer
186 views

Heat preserving performance of container relative to content

This question has been addressed in the case of a thermos bottle: Performance of a thermos bottle relative to contents I am asking the question again without the hypothesis that it is a thermos ...
9
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2answers
4k views

Infrared remote flashes blue light in camera

I know that if you held an infrared remote in front of a digital camera, it'll flash a blue/purplish light when you press the buttons. Why? (Image by Zombie Rider.)