Applies to questions related to common objects and frequently experienced effects. Typically, these questions require explaining how the laws of physics are applied to a common situation, how objects work, etc.
23
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12answers
1k 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.
22
votes
6answers
2k views
How do whisky stones keep your drink cold?
From a discussion in the DMZ (security stack exchange's chat room - a place where food and drink are important topics) we began to question the difference between how ice and whisky stones work to ...
20
votes
8answers
2k views
Why doesn't the bike fall if going with a high speed?
Why does the bike fall when its speed is very low or close to zero and is balanced when going with a high speed?
19
votes
3answers
553 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 ...
19
votes
3answers
369 views
How much information about the scale of a waterfall can be obtained from its sound?
Is it possible to constrain the height, volume flow, or distance of a waterfall from the quantitative analysis of a high-quality recording of its sound?
As an aside, the simulated sounds of fluid ...
16
votes
2answers
241 views
Stripeless cleaning of windows
Cross post: http://chemistry.stackexchange.com/q/4377/22
Last week I was discussing with a friend how we thought the stripeless cleaning of windows is achieved when using a cleaner like Windex ...
15
votes
11answers
1k views
Are there still 'everyday' phenomena unexplained by Physics? [closed]
There are two very famous quotes from German Nobel Laureate Albert Abraham Michelson that are remembered mainly for being extremely wrong (especially since he said them just before two major ...
13
votes
1answer
199 views
Modelling the movement and jumps of a chalk while drawing a dashed line on a blackboard
You probably know that if you try to draw a line using a piece of chalk on a blackboard , under some conditions (for example, $\alpha<\frac{\pi}{2}$ in the picture below) you will have a dashed ...
13
votes
1answer
246 views
Why is boiling water the second time more quiet than boiling it the first time?
First of all: This is a different question than Why is boiling water loud, then quiet?, although the answers might be similar.
When I wake up, I boil some water for a cup of tea. It happens quite ...
13
votes
2answers
464 views
What causes ballpoint pens to write intermittently?
After a while, a ball point pen doesn't write very well anymore. It will write for a little distance, then leave a gap, then maybe write in little streaks, then maybe write properly again. It seems ...
12
votes
5answers
1k views
Why Won't a Tight Cable Ever Be Fully Straight?
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 ...
12
votes
6answers
871 views
Does an empty refrigerator require more power to stay cold than a full one?
Given that everything else is equal (model of fridge, temperature settings, external temperature, altitude), over a given duration of having the door closed, does it require more electricity to cool ...
9
votes
8answers
2k views
Why do ice cubes come out easier from top trays?
This is my "hey, I've noticed that too!" question for the week. If you stack two plastic ice cube trays with water in them in a freezer, the resulting ice cubes in the top tray will usually come out ...
9
votes
1answer
780 views
Why does paper become transparent 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 transparent; but when I attempt the same with water it doesn't as much. Why?
9
votes
3answers
202 views
Does sound propagate further in freezing weather?
A few days ago I went for a walk in the evening. We're having winter with a little snow and freezing temperatures. We're in a quiet, shallow valley with a train station about 1km from us. I heard a ...
9
votes
4answers
636 views
Does it matter how you order your tug-of-war participants?
In a tug-of-war match today, my summer camp students were very concerned about putting the biggest people at the back of the rope. Is there any advantage to this strategy?
8
votes
3answers
528 views
How hot is the water in the pot?
Question: How hot is the water in the pot? More precisely speaking, how can I get a temperature of the water as a function of time a priori?
Background & My attempt: Recently I started spend ...
7
votes
2answers
825 views
How can rising bubbles shrink and disappear?
I was recently looking at a Wurlitzer juke box, and noticed something strange. It's decorated with liquid-filled tubes. Gas bubbles are injected at the bottoms of the tubes, and the bubbles naturally ...
7
votes
3answers
315 views
Would a bicycle stay upright if moving on a treadmill and why?
I suspect not, because moving forward (or backwards for that matter) is an important part, but I would like to confirm.
UPDATE: Clearly it's possible
...
7
votes
2answers
218 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 ...
7
votes
1answer
109 views
What determines bubble locations in boiling water?
Something a little different to our usual fare. I was boiling a pan of water for cookery the other day, and got to wondering what caused the location of the bubble streams from the bottom of the pan. ...
6
votes
6answers
544 views
When driving uphill why can't I reach a velocity that I would have been able to maintain if I started with it?
Consider these two situations when driving on a long straight road uphill:
Starting at a high velocity $v_h$, which the car is able to maintain.
Starting at a lower velocity $v_l$, and then trying ...
6
votes
4answers
337 views
What happens when we cut objects?
What is the role of the molecular bonds in the process of cutting something? What the one of the Pauli exclusion principle, responsible for the "hardness" of matter?
Moreover, is all the energy ...
6
votes
1answer
124 views
What is the angle at which water is splashed when a vehicle tyre rides in water on the road?
I would like to know the following:
What is the angle at which water gets splashed when I ride my vehicle through a water on the road?
How does angle of water varies with speed?
What is the relation ...
5
votes
4answers
978 views
Should I heat my room when I'm not here, energy-efficiently speaking?
I was wondering as it's getting cold : is it better for my electricity bill to shut down completely my (electric) heater during day, and to turn it on again when I come home (then it will have to heat ...
5
votes
7answers
5k views
Why won't my door close in the winter?
Please, take this question seriously, because this is a real problem to me. I have a door in my flat. A closet door, to be specific. And there is a problem with it.
In the summer everything is ok, ...
5
votes
3answers
480 views
Get an intuition for pressure values
I am currently working with pressure differences in the milibar range. However I do not have a good feeling for pressure differences. In every day life:
Where does a pressure of say 100 mbar over ...
5
votes
3answers
149 views
Why is the meander ratio of a river $= \pi$?
To get from point $A$ to $B$, a river will take a path that is $\pi$ times longer than as the crow flies (I think this result is from Einstein). What is the proof of this, and how well does it hold ...
5
votes
4answers
171 views
Can a balloon be used as an anchor point for a pulley?
For a physics/ engineering contest, I want to use a large balloon as an anchor point for a pulley. This would allow me to raise and drop masses.
However, in testing, when I pull on the pulley the ...
5
votes
1answer
971 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 ...
5
votes
3answers
226 views
How can I determine the coefficient $k$ in $ \dfrac{dT}{dt} = -k(T - 100 \mathrm{^\circ C}) $?
I recently spend some time on cooking and I'm curious about the time evolution of the temperature of the water. I did some experiment and the temperature is of the form
$$ T = 100 \mathrm{^\circ C} + ...
5
votes
2answers
137 views
Why does motion help you balance on ice skates?
It's almost impossible to balance on a single ice skate if you're standing still. But give yourself just a little forward motion—it doesn't take very much—and it suddenly becomes easy. You can stand ...
5
votes
1answer
184 views
What is the roaring in a roaring fire?
I was just starting a barbecue fire by blowing on the smouldering coals when I realised I had no idea what the sound was actually caused by. I can make the sound by blowing at almost any flame I can ...
5
votes
1answer
494 views
Why do mirages only appear on hot days?
A previous question asked why the road sometimes appears wet on hot days.
The reason is that when there's a temperature gradient in the air, it causes a gradient in the index of refraction, causing ...
5
votes
2answers
255 views
Why does a firebrand glow brightest before it burns out?
I've noticed this in match-sticks, and mango wood. After the flames die out, the brand glows red for a while. The glow is brightest right before it dies out.
My guess is that immediately before the ...
5
votes
0answers
191 views
Neodymium Electromagnet?
I am interface designer that occasionally steps out and does some product/concept design. The last one I'm working on is something that would require me to make a matrix of little electro magnets, and ...
5
votes
0answers
179 views
Where to place a fan in order to cool a room the fastest [closed]
Imagine I have room that is very hot and it is colder outside. I want to cool it down using a fan.
Scenario 1
There is only one door. I have one fan.
Where should I put it and which way should it ...
4
votes
3answers
3k views
Why can't helicopters reach mount everest?
Is there a reason why people can't just take the helicopter to mount Everest? Why is it that helicopters can't reach that high?
4
votes
1answer
95 views
Physics of every-day life: rotating bag of tea
Whilst studying for my physics courses, I like to drink tea. Today, I noticed that if you pull a bag of tea out of a hot cup of water, it gradually starts to rotate, picking up speed as time ...
4
votes
3answers
224 views
Why don't electric workers get electrocuted when only touching one wire? [duplicate]
I know that when electricians work on the poles on the streets, if they only touch one wire at a time they will be fine. However, from my understanding, the negative wire is connected to a large ...
4
votes
1answer
1k 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 ...
4
votes
2answers
213 views
How can one feel cold without touching it?
Let me explain.
My shower is inconsistant in how hot it gets. Whenever I turn on the shower, I always put my hand really close to the water, but not touching it, so I can feel the heat radiate from ...
4
votes
1answer
134 views
The feeling of fuzz on the display surface of a Cathode Ray Tube Television
I was always wondering where the feeling of fuzz comes from when touching a CRT (Cathode Ray Tube) television on its display screen when the TV is turned on. Can someone please explain why I feel ...
4
votes
1answer
252 views
What is the purpose of a “protect from light” warning?
Some food or medical items, like rasberry juice concentrate I just bought, have a "protect from light" warning on the label. How can light influence products like milk and what does this warning mean ...
4
votes
1answer
77 views
How does my hand amplify an FM radio signal?
I have a gizmo that broadcasts an FM radio signal from my phone's headphone socket to my car's radio antenna.
Sometimes, there's another station on the same frequency with a stronger signal and my ...
4
votes
2answers
339 views
Why does the higher of two medical IV bags empties first?
I'm a nurse, so my physics background is about that of a lay person. Please explain on that level. Ordinarily an Intravenous (IV) fluid bag is one liter. An IV piggyback is usually 2500ml. usually the ...
4
votes
1answer
674 views
Why does it spark when I push a plug in the electrical socket?
When I slowly push a plug into the electrical socket I can often see sparks. Can anybody explain why? Can this be possibly harmful for the devices I plug in?
4
votes
1answer
46 views
What is the minimum pressure difference for your ears to pop?
I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
4
votes
1answer
137 views
Why do rain waves form and what is their connection to the texture of the surface they're on?
When it rains and water flows down an inclined street, ripples may form that are carried along with the current. Here's a picture with an example of what I'm talking about
I'd like to know what the ...
4
votes
2answers
235 views
Why do books have dog ears?
I googled the question and found no explanation. It seems that dog ears are inevitable (for paperbacks, notably) even if you've always been careful. From my experience, they are about equally likely ...
