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

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Who does work while walking?

While walking the work done by friction is zero. But who does the work, actually? How someone is getting displaced? This situation also arises when someone climbs without slipping or is climbing a ...
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3answers
7k views

Pressure inside a light bulb

It is known that nowadays most light bulbs are filled with gas in order to minimise the evaporation rate of tungsten. Is e.g. argon put into the bulb with reduced pressure, so that the glass doesn't ...
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1answer
139 views

energy efficiency - dryer vs hang+dehumidifer

When I have wet clothes coming out of the washing machine, I can either tumble-dry them in an electric clothes-dryer, or I can hang them to dry. But I can only hang them in a basement. The basement ...
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1answer
134 views

Is putting a charged balloon up to a neutral wall polarization AND temporary induction, or just polarization?

Is putting a balloon that is charged up against a wall and having it stick polarization AND charging by temporary induction, or just polarization?
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1answer
56 views

What is “wrong” with this microwave?

Metal objects in microwave ovens are known to be somewhat dangerous. However, my microwave has the following label stuck inside: It seems to imply that this particular oven forbids heating drinks ...
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2answers
244 views

Will an object with a higher temperature lose its heat faster than a cooler, yet warm object

I'm after the math, which I don't understand yet and can't find elsewhere. The variables are: Two identical cups, A and B The same volume of fluid is contained in each cup, test fluid is water. ...
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1answer
75 views

Adding cinnamon to my coffee makes it stop whirling much faster: Why is thats?

When I stir my coffee in a cup, the fluid spins a long time, but when I pour cinnamon into the cup, the spinning fluid slows and stops very rapidly - why?
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0answers
19 views

How does it takes to deadlift a sports car? [duplicate]

In the movie Furious 7, Dom lift a Lykan HyperSport with bare hands. Given that in reality, how strong it has to be to lift a Lykan HyperSport(1,380 kg), says to 40 cm in one rear end, and hold it ...
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5answers
3k views

Why Does Angular Velocity Increase as Radius Decrease?

Suppose a child were to ask you why a tetherball (picture below) seems to speed up as it wraps around the pole. How would you explain this to them? Certainly you wouldn't say something like, "Angular ...
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10answers
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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, ...
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11answers
2k views

Backyard experiments to falsify the Flat Earth theory [duplicate]

I recently became aware that the flat Earth theory still exists in the 21st century, and has colored the views of a friend of mine. Roughly speaking, the tenets are: The Earth is a flat disk, with ...
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2answers
11k 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 ...
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0answers
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Why should I discard a carafe if it has ever been heated empty? (Can thermal shock permanently weaken materials without causing them to fail?) [closed]

Related to "What pressure or tension occurs in a glass jar when I pour boiling water inside?" I just got a new coffeemaker, and one of the warnings in the manual states that you should discard the ...
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1answer
45 views

Nail clippers and conservation of momentum

As I clip my fingernails using nail clippers, pieces of nails sometimes fly off violently, reaching the other end of the room. What's happening in terms of conservation of momentum, how are the pieces ...
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2answers
87 views

Would you save energy by heating the air in a shower stall so that you could use colder water?

It is refreshing to take a cool shower in hot weather. And for the sake of discussion, lets assume that one should be "comfortable" with temeratures when taking a shower. Considering that the vast ...
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1answer
294 views

Suntan: UV absorption vs daytime

I guess that these questions were being asked by many people on the Northern Hemisphere during this summer (and other summers) and someone may give a nice, coherent answer. The general question is how ...
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1answer
42 views

Why do i see more steam coming out from the vessel containing water after i turned off the stove? [duplicate]

It is a little observation i did when i was boiling the water. what i observe is that when i turned off the stove on which the water was boiling i could see more steam coming out from it than the ...
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1answer
49 views

Are low pressure and high pressure areas responsible for rain?

My understanding is that low pressure areas are susceptible to rain. However, high pressure areas have no rain. Now, I want to correlate this with the following areas - Lower Hutt, Wellington , NZ - ...
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4answers
4k views

Do objects gain and lose heat at the same rate?

For example, if I take an item out of the refrigerator, set it on the counter for a period of time, allow it to warm up a bit (but not so long that it reaches room temperature and stabilizes), and ...
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0answers
93 views

My bathroom door stays open in summer [closed]

My bathroom door remains open in summer, but in the winter it stays about halfway between fully open (90 degree angle, against a window) and closed. The door is between bedroom and bathroom and it is ...
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0answers
23 views

Theoretical model of MRI scanner

Recently I have gained strong interest in studying the Physics of an MRI scanner. Most of the physics resources I have found are strongly practically orientated and do not so much approach the ...
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8answers
452 views

Why not use our own light production to produce new energy instead of wasting it?

Why don't we use our own light production at night (I mean home, buildings, streets,..., lighting) to charge photovoltaic panels instead of wasting it?
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2answers
27 views

How does liquid stay in a Pasteur pipette/eye dropper instead of dripping out?

From what I understand about how pipettes work (correct me if I am wrong), when you squeeze the bulb of a pipette, you are removing the air from it and when you dip the end in liquid and release the ...
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0answers
18 views

The frequency induced by the alternating current

Let set up the experiment as followed. A string is stretched at two ends. Two magnet poles N and S are placed under and above the string. Now we let an alternating current go through the string with ...
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1answer
72 views

How much money can I save on gas by losing weight?

I read somewhere that if you carried around a penny in your car, over the lifetime of the car, you would end up paying an extra penny in gas than if you weren't carrying that penny. I was wondering ...
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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. ...
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2answers
30 views

Wall vents in house and heat loss

I live in northern midwest of USA--have propane central heat. Electricity is cheaper here than propane sometimes. To aid in heating front room I have 2 electrical space heater--one with fan,and one ...
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1answer
336 views

Why is it difficult to ride a bicycle with a partially inflated or deflated tyre?

It is a common observation that riding a bicycle with an inflated tyre is easier than riding one with a deflated tyre but why is it so? As per my knowledge in an ideal case of no deformation in ...
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2answers
305 views

What determines the sharpness of a shadow?

What are the factors that affect the sharpness of a shadow? I would think that the distance between the light source and the object, the distance between the object and the shadow, and the size of ...
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2answers
592 views

How does the magnetic field get induced in car's tire?

I was amazed to see how my car's tire started attracting the nuts and bolts, how in the world did it induce the magnetic field? Never heard of such phenomena!!!
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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 ...
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1answer
155 views

Rotation motion like the number 8

I'm a college student majoring in culinology and I'm trying to find out the reason or method of the number 8 motion. Responses doesn't have to be in culinology examples, but that would be a great help ...
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1answer
9k views

Why does a car go down the hill backwards even though the engine keeps running? [closed]

I dont get why a forward gear allows sliding a car backwards. Any ideas? So this is a car with an automatic transmission. The transmission is in the drive mode (move forward). Car is at the slope ...
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2answers
33 views

Can a floor made of copper pennies produce a static electric shock?

A friend is going to install thousands of pennies in a mosaic layout to be used as flooring in his home. Can this floor produce a static electric shock when walking on it? Is it possible to ...
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4answers
3k views

Why can't echoes be heard inside a room?

If I go camping and shout anywhere, in the forest or on a cliff, I usually hear the echo of my voice. Why when I shout in my room I do not hear any echoes?
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0answers
17 views

Prismatic shaped rear view mirrors

To reduce the intensity of the incident light, prismatically shaped rear view mirrors are used in cars with a day-night switch which changes the angle such that instead of the polished surface ...
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4answers
5k views

Physics of a burning log of firewood

According to my knowledge, heat is nothing but the result of the vibrations of atoms and molecules. I guess this mean that in heating up a gas or liquid, we are increasing the rate at which the ...
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3answers
57 views

When walking, why the foot which get the reaction doesn't accelerate?

To walk we apply a force and the earth gives us a reaction. But the foot which get the force doesn't accelerate.
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2answers
929 views

Will a tall narrow cup keep a cup coffee warmer than a more evenly dimensioned cup?

I noticed a colleague had a tall narrow cup for his coffee, and it got me thinking about whether it would retain heat for longer or not. Assume two cups, both are cylindrical, and both hold the same ...
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1answer
151 views

Jumping from a moving train

If you were to jump from a moving train at 20 km/h, would it be better to run in the direction of movement before jumping to maintain inertia or in the opposite direction of the train ?
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1answer
63 views

Is it a law of physics that all machines will break?

The question sounds kinda dumb when I say it out loud but at the same time I'm very curious. When things break, is it solely due to an intrinsic design flaw or is it due to entropy? And is the ...
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2answers
2k views

When a drop of water falls into water, where do the splashes come from?

When a drop of water falls into a reservoir of water from a high enough altitude, water droplets will splash (image credit): My question: Does the water in those droplets come from the original ...
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5answers
709 views

Can we create invisible things?

We are able to see this beautiful world because of light. When light gets reflected from the object, the reflected light enters our eye retina and thus we are able see that particular object from ...
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2answers
1k views

How does a table fan work?

In a table fan, the blades move around in circular way and we feel air/wind when sitting on front of it. How does this happen?
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2answers
48 views

Unusual phenomenon from fluorescent lightbulb

Next to my bed I have a fluorescent desk lamp. One night, after I had turn off all the lights in my room, I grabbed my blanket from the other end of the bed. As I grabbed the blanket, one end of the ...
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0answers
28 views

Approximating Gallons of Gas Needed for Trip (read: physics grad. with too much free time)

My departure from college has left me with an itch for physics-y problems to solve, and my boredom and free time gave way to this approximation of the gallons of gas I use for the trip to my ...
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0answers
77 views

I don't see that general relativity is really needed for GPS to work correctly [duplicate]

From what I understand, GPS localization is based on the difference in the reception time from the time of emission of a signal from different GPS satellites whose positions are known. For this we ...
29
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3answers
933 views

Why do particles in the molten wax near a burning candle wick get pushed away?

Have a look at this clip I made of my candle burning: I can accept that the molten wax gets sucked into the wick (though not quite sure why: capilary action?). But why does it also seem to get ...
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1answer
1k 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. ...
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2answers
4k views

Can sugar be affected by a magnetic field?

While I was making a morning coffee at work, some sugar from the spoon started to fly away, seemingly towards some foam cups. Can this be explained by magnetism?