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.

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2
votes
1answer
114 views

Balloon Inflation

I am planning to use an air compressor to inflate a rubber balloon. I need to size the compressor for inflating the balloon, but for sizing the compressor I need the pressure required to inflate the ...
0
votes
1answer
900 views

What force does bathroom scale measure?

When you stand on a bathroom scale, I know that the force displayed is the normal force. Since it is the normal force, then technically the force displayed would actually be Fg= (mass)(acceleration) ...
25
votes
3answers
3k views

Where does the light go when I turn off the light switch?

As above... Surely it must go somewhere? My child asked me this question and it was a difficult one to answer.
78
votes
23answers
7k 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 ...
1
vote
1answer
103 views

Calculating Mass for a Reduced Trajectory while Keeping Projectile Force Constant

Apologies if this is not a research-specific question, but applied mechanics. A firefighter has to pass a test in which he is to throw a medicine ball a certain distance. The ball is thrown at a 45 ...
11
votes
1answer
2k views

How do they measure the rotational speed of cricket balls?

The 2013 Ashes series (a cricket thing between England and Australia) are underway as of today and it seems they have a new (to me) gimmick. It appears that they are now able to measure almost ...
5
votes
2answers
306 views

Why can't I slap an insect into unconsciousness?

So it is summer, which means I have to deal with insects. Today one has made it into my room and while I tried to work this insect was constantly in my face, which caused me waving my hands in the ...
10
votes
2answers
488 views

Movie airplanes and suction

Having watched a recent action movie (with zombies in it) I wondered whether the suction from a hole in the airplane's hull would really be able to rip out luggage, persons and even seating benches. ...
24
votes
6answers
2k 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 ...
0
votes
0answers
67 views

When to dump water from a water cooler

If space in your cooler is not an issue and you're not concerned about other issues associated with water collecting in your cooler, under what conditions should you dump water from your cooler if ...
1
vote
2answers
100 views

Extreme heating by Sun on Earth- Can eggs be fried?

Will it be possible to fry eggs in Sahara desert by just keeping them under the sun? If so, then will the radiated eggs be any different? Or will we have to use the solar cooking concept to some ...
0
votes
2answers
241 views

Why do we feel a sudden chill?

When we are in a room, especially in some old houses, we feel this sudden rush of cold air. How does a strong air current arise and pass away so quickly?(lasts for about a second) I know air-currents ...
14
votes
2answers
512 views

Are these sunglass lenses linearly polarized or what?

This is a difficult question to phrase, so please bear with me. I found some cheap sunglasses and pulled out the plastic lenses which are polarized. For clarity, I have labeled them as lens-1 and -2 ...
6
votes
1answer
409 views

How does sun light after it has passed window's pane still heat me up?

I believe it is so because most of photons' energy has successfully passed the glass. But is it so? And how can I roughly estimate part of light's energy which will pass obstacles like glass? And how ...
8
votes
1answer
668 views

Are two thin blankets significantly warmer than a single thick blanket?

Almost every source I can find online maintains that two 0.5 cm blankets are significantly warmer than a single 1cm blanket due to air trapped between the thin blankets. However, the thermal ...
1
vote
1answer
106 views

Why does water freeze at $0~^\circ\text{C}$ while poultry freezes at $-2.2~^\circ\text{C}$?

We all know the freezing point of water is $0~^\circ\text{C}$, however correct me if I'm wrong, but I believe the freezing point of poultry (which I'm guessing means water in poultry) is ...
3
votes
2answers
290 views

How fart is transported through air?

As we know diffussivity of gas is really slow (e.g. $\require{mhchem}\ce{O2}$ and $\ce{H2O}$ in the air are respectively $0.176$ and $0.282 ~\text{cm}^2/\text{s}$). here is a example to specify how ...
8
votes
4answers
1k views

Does ABS shorten stopping distance of a car?

ABS, from German Antiblockiersystem, is a device put in almost every new automobile. The web has lots of explanations about the system, how it works, but I don't understand how it shortens the way of ...
7
votes
1answer
598 views

What part of the fan blade actually does the noise generation?

I'm trying to identify the sources of noise in spinning fan blades and what causes them. Is the noise only generated by the lead edge of the blade 'cutting through' air? and different parts of it ...
28
votes
3answers
1k views

Floating a ping pong ball in the air just using a pen!

Caution: Apparently this problem is harder than it seems! There is a well known phenomena, which I first learnt about when I was a 10 years old kid. You can levitate a ping pong(or whatever ...
0
votes
1answer
95 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 ...
-1
votes
1answer
92 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 ...
3
votes
2answers
230 views

Why do some air-conditioned stores blast you with jets of air as you enter?

I went to a grocery store on a hot day that was very well air-conditioned, and I noticed as I went through the open entrance that there seemed to be a very powerful downward air current right at the ...
6
votes
2answers
371 views

Why do objects sometimes fall on their own?

I have observed sometimes that when I keep some objects precariously balanced, for e.g. some objects in a cupboard, they seem quite stable at the time when I place them there but after a certain ...
8
votes
2answers
201 views

Why is the summer, in the temperate latitudes, in average, hotter that the spring?

It is common knowledge that the transition from the Spring to the Summer season occurs in the Summer Solstice when the "Sun reaches its highest excursion relative to the celestial equator on the ...
3
votes
2answers
491 views

Performance of a thermos bottle relative to contents

I'm not a physicist but I majored it at high school (a long time ago) and I study university math. Me and my roommate discussed whether the performance of a Thermos bottle is influenced by how full ...
2
votes
2answers
111 views

Is an ice globe the worst possible way to cool a drink (with ice)?

Given an alcohol solution and a mass of ice in whatever shape you like, is shaping it into a sphere the worst possible way to cool your drink without diluting it? If the ice starts off at a sub-zero ...
19
votes
4answers
1k views

Does a car consume more fuel when it's raining?

Yesterday my wife asked me that question, and I couldn't answer. Consider a car, in a sunny day, and that is consumes x gallons per mile. Considering that everything is equal, except that it's ...
5
votes
1answer
124 views

Why do baked goods “fall” if exposed to sudden cooler air?

This is a know rule when baking: Don't open the oven until your cake is finished, otherwise it will "fall". Why/how does this happen?
-1
votes
5answers
3k views

Is it possible to generate electricity using a water tower?

Is it possible to build a water tower that will provide enough pressure to run an electricity generator? A water pump can be used to send water up to the tower. The water pump can be powered by solar ...
-1
votes
2answers
323 views

6 Story Building Swaying, Normal? [closed]

Preface: I'm currently sitting at my desk on a 5th floor in a South Florida office building, as I was earlier this morning when I felt the building sway slightly. It wasn't continuous and the ...
7
votes
1answer
186 views

Ringing sound when you flip a coin?

When you flip a coin, you hear a ringing sound. I know that the source of the sound is the thumbnail hitting the coin, but it seems to be filtered by the spinning of the coin. Specifically, the faster ...
41
votes
8answers
2k views

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 ...
4
votes
2answers
941 views

Why does the Sun feel hotter through a window?

I have this big window in my room that the Sun shines through every morning. When I wake up I usually notice that the Sunlight coming through my window feels hot. Much hotter than it normally does ...
-4
votes
2answers
5k views

Why two balls of different mass dropped from the same height falls the ground at the same time? [duplicate]

When two balls of different masses, thrown from equal height they reaches the ground at the same time. Can anyone explain this in terms of laws of Physics(or with mathematical equations)?
1
vote
1answer
163 views

Optical illusion of car wheels, speeding up

Perhaps it is some free moving spinner attached to the wheel, but as opposed to this question: Why does the wheel of a car appear to be moving in opposite direction? I have seen car wheels that appear ...
5
votes
1answer
186 views

What exactly heats a pool of water on a sunny day

On a sunny day an outdoor swimming pool will heat up fairly quickly. My question is, what is the exact mechanism for this and can we put numerical figures on it? Given that water is clear and ...
4
votes
1answer
227 views

Why do ice cubes make a cracking sound when placed in fizzy wine (Prosecco)?

When placing ice cubes in a fizzy drink such as Prosecco, ice makes a cracking sound, after which the fizzy bubbles more than usual. What is the physics of this phenomenon?
18
votes
3answers
3k views

Is play-dough liquid or solid?

At room temperature, play-dough is solid(ish). But if you make a thin strip it cannot just stand up on it's own, so is it still solid? On a more general note, what classifies or differentiates a ...
18
votes
2answers
645 views

How hot does the tip of a pencil get while writing?

When writing with a pencil, there seems to be quite a lot of friction - which seems like it would induce heat. How hot would the tip of a #2 pencil get writing on normal copy paper?
7
votes
1answer
742 views

How does the boiling time depend on the number of eggs

My nephew showed me an exercise from his school-textbook about boiling eggs. Here is the exercise (translated from german): To make one hard-boiled egg in a pot of water one has to put it for 8 ...
9
votes
2answers
882 views

How does a sponge “suck” up water against gravity?

If I take a sponge and place it in a shallow dish of water (i.e. water level is lower than height of sponge), it absorbs water until the sponge is wet, including a portion of the sponge above the ...
3
votes
2answers
124 views

Cycling down a mountain

I am Dutch, so I cycle a lot, hence the following question. Say I am standing at the top of a mountain on my bicycle. I have an amount of energy $E$ available. Say that after the slope of the mountain ...
2
votes
2answers
101 views

Harmlessness of a pure alpha decay particle

From my high school physics class I remember that there are some particles which exhibit pure alpha decay (i.e. alpha decay to there stable isotope), like Po-210, Po-211 and Bi-209. What I also know ...
-2
votes
1answer
78 views

How does the formaldehyde leak into the food from bamboo cutting board? [closed]

http://food.thefuntimesguide.com/2010/07/bamboo_cutting_board.php Some bamboo cutting boards are glued together with adhesives that have formaldehyde in them — which could eventually leak into and ...
1
vote
2answers
158 views

Can random constructive interference with sound waves cause damage?

Any two sound waves have a random chance to constructively interfere with each other at a given spot and this will cause an increase or decrease in pressure. So is it possible that a large number of ...
6
votes
1answer
273 views

The quickest 6-3 play in baseball: to bounce or not to bounce?

What's the quickest way the get the ball (say from shortstop) into the first-baseman's glove, given some fixed initial (throwing) speed? Directly or with one bounce? I'm fairly sure that the answer ...
11
votes
2answers
695 views

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 ...
0
votes
0answers
47 views

Color of sky scattering by sky dust [duplicate]

Why does we see sky like blue in maximum time? We know violet has less wavelength, so we should see sky like violet. My assumption is that, violet is not primary color and not sufficient in the ...
1
vote
1answer
641 views

Calculate the distance between two points from iPhone Camera

I want to calculate the distance between two objects using an iPhone camera. Suppose I'm standing with my iPhone 10 feet away from the objects. Now, I want to calculate the distance between those ...