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

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8
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2answers
147 views

Why do headphones tangle themselves whereas shoe laces untie themselves?

Why do headphones tangle themselves whereas shoe laces untangle or untie themselves? Why aren't we using the phenomenon to create headphones that tangle less and shoe laces that untie less?
47
votes
2answers
8k views

Why do I see better under water using swimming goggles? [duplicate]

I am myopic (I don't really know if this is relevant or not) and I usually swim without contact lenses. My vision is clearly better underwater when I am using swimming goggles. I have tried to ...
0
votes
1answer
48 views

Is it scientifically possible to stop a screens polarization by adding a layer? [closed]

Back story: At work we deal with confidential data, however our desk layout does not allow for screen privacy. We do not a privacy screens and are not allowed to take apart our screens. In searching ...
0
votes
1answer
55 views

Hard drive disk seems to “move” its weight when running

I have an external box for hard drives and plugged a broken hard disk to it. Then I turned it on and took it in hand. Now, if I gently tilt and turn the box on its axis, the weight seems to "go" in ...
1
vote
0answers
25 views

Optimal two-stage warming up of a bottle of baby milk

Here's a common two-stage method to warm up a bottle of baby milk to avoid uneven milk temperature: 1) Heat up a bowl of water in a microwave oven. 2) Put the bottle into the bowl of heated water to ...
1
vote
4answers
103 views

Why adhesion is stronger at faster peeling rate?

Adhesion is strong at fast peeling rates and weak at slow peeling rate (paper, video; Newtonian adhesive, non-Newtonian adhesive?), i.e. it is rate-sensitive. Why? (source: Meitl et al.: thanks to ...
0
votes
3answers
95 views

Lifting and putting down a weight

A man in a gym lifts a weight and then puts it down where it was before. 1) What can be say about the work done by the man to the weight? 2) Can it be equal in absolute value to the work made by ...
3
votes
1answer
88 views

Why purple seems so to similar to red? [duplicate]

Purple lights has the highest frequency among all visible lights, while the red lights is the least frequent one. However, purple seems to be a mix of red and blue to human eyes, why?
3
votes
1answer
42 views

Slackline tangling

This question is about random formation of knots in a systematically tied rope. I will give some background, hope that does not make it off-topic. In climbing (and sailing) one has to store very long ...
4
votes
4answers
336 views

Why do wheels spin?

I'm pretty sure this is probably a stupid question but it is annoying me a lot. In my physics textbook it says, cars move because the wheels exert a backward force on the ground and the ground exerts ...
1
vote
1answer
83 views

Patterns in falling viscous fluids

It is a common observation that honey(or any other viscous fluid),tends to overlap/coil/wind up as it reaches the rigid surface. There is this little bend near the pile-up. Why is this so? How does a ...
1
vote
1answer
71 views

Mechanics of a falling cat [duplicate]

It is a general statement that cats tend to fall on their feet. How far is this is a valid statement? If I were to drop a cat from 50 meters height, feet up(hypothetically), would it still land on ...
0
votes
1answer
74 views

Is a laminated padlock really stronger than a solid one, and if so, why?

I used to think that the padlock design of using many layers of metal stacked to form the main body was a cost-cutting consideration. This was my assumption before I came across the idea that it was ...
3
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2answers
57 views
4
votes
1answer
107 views

Why doesn't spaghetti knot when stirred?

When I cook spaghetti, they never tangle themselves so much to form knots, neither when in the boiling water nor when they're mixed with sauce. Why is this so? I experience this behaviour both with ...
1
vote
0answers
39 views

Direct comparison of energy measurements for kids

I am planning a few physics & science sessions in the woods with 14 year-olds. The theme for one of the sessions is Energy, and my aim is to show them how gravity, solar radiation, wind (air ...
55
votes
3answers
10k views

Why do beams of light (from torches or other directed sources) not extend to infinity?

When I'm in a dark environment, and I turn on a torch, I can see the beam of light from the torch. To the best of my understanding, the main reason why I can see the beam of light is that the light ...
4
votes
1answer
145 views

Entropy change in a boiling egg

Yesterday in a rather intuitive Q/A session, by a visiting researcher in my town, this question got my attention.What he said was that if you boil an egg, the entropy inside the egg would increase.Now ...
0
votes
1answer
36 views

How does the jumper in Christmas lights work?

This is the structure according to my textbook: I don't know what the glass insulator are for?? But there is indeed a thin layer of insulator coating on the jumper. Why I don't know, too, what that ...
1
vote
0answers
69 views

Please explain this optical phenomenon, as seen from the top of the cup [closed]

So here is a cup, and i poured some water in it. The question is why do i see those multiple reflections? What causes these images?
120
votes
2answers
9k views

Why does a mirror split my laser beam?

Last night my daughter was asking why a mirror "always does that" (referring to reflecting a spot of light). To help her figure it out, I grabbed my green laser pointer so she could see the light ...
3
votes
1answer
207 views

If my windows are open on a windy day, the curtains sway and the doors slam shut. Why don't I feel this wind?

I am standing indoors, right in front of my open window, as I see my curtains moving back and forth and I can hear my closed doors shaking. I can also hear the wind howling loudly. Why don't I feel ...
0
votes
1answer
31 views

Windchill effect or something else

If I'm driving a fire truck on a cold winter night, given the following factors. Will it create an effect that could freeze the water pump faster than if it were just parked in the same conditions. ...
4
votes
1answer
63 views

Why does wind sound the way it does?

You can obviously hear wind. From everyday experience, the stronger the wind, the louder its sound. But this sound is always similar, and quite distinctive, noise-like. Can one compute the spectrum ...
-4
votes
3answers
88 views

Doesn't any massive conductor look like “ground” to an AC supply?

I've been puzzling over this excellent answer to the perennial "Why don't I get shocked by a hot wire if I'm not grounded?" question. The orders of magnitude just don't seem right for two reasons: ...
3
votes
2answers
1k views

How does making “pyramid hologram projectors using smartphones” work?

The basis of this question is this video, where a 3D hologram like effect is achieved using a 4 sided hollow pyramid. I don't know if this is holography in the usual sense. Can some one explain this ...
3
votes
2answers
63 views

Can wind be defined as momentum/mass of air molecules?

In the past I thought a breeze of wind was "made" from a large amount of air molecules going all the same direction in the same speed. But it's not like that, actually this voted answer, this site, ...
1
vote
0answers
150 views

Why do trees sway?

Resonance can also occur in three dimensions (such as wind induced swaying) I tried to make a free body diagram (I know it is terribly wrong) to find the forces that causes the tree to undergo ...
6
votes
2answers
322 views

How much upward force due to ground vibrations does the Earth exert on you?

Say you're walking by the highway and you can feel the vibrations of cars moving along. How would you approximate the force that the ground is exerting on your feet due to these vibrations?
3
votes
2answers
132 views

Why do tires with low air pressure experience more friction?

How does tyre pressure affect the frictional force on a tyre even though friction is independent of area of contact? And how does one analyze or calculate this friction?
7
votes
2answers
1k views

Why do chocolate bars usually break at the cleavages?

Why do chocolate bars usually break at the cleavages? The chocolate bar is less thick at cleavages. How can we relate thickness and fracture point of chocolate bar?
0
votes
2answers
50 views

Speed of a cycle wheel

Common sense tells me that the front wheel is going at the same speed as the back wheel, but somewhere, the phrase 100% efficient keeps nagging at my brain. That's because, I somehow feel that ...
-2
votes
1answer
113 views

What is the meaning of this Feynman's statement? [closed]

Richard Feynman has a strange statement in first lecture of his known book "Feynman Lectures on Physics. He says If a piece of steel or a piece of salt, consisting of atoms one next to the other, ...
0
votes
2answers
46 views

Explanation of duration of forces due to electrostatic charge

when we use the pen and make the rubbing in it the pen can attractive the paper and after 1 sec. the paper fall down because it loss the earned energy but in this video the balloon still attractive ...
5
votes
2answers
135 views

If pencil tip is heated why doesn't it write?

Why doesn't a pencil write if its tip is heated in a candle flame?
4
votes
1answer
269 views

Should I place a spoon in a cup of liquid before heating it in a mircowave?

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 ...
1
vote
1answer
92 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?
1
vote
0answers
20 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 ...
22
votes
11answers
3k 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 ...
1
vote
0answers
113 views

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 (...
2
votes
1answer
78 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 ...
5
votes
2answers
117 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 ...
1
vote
1answer
69 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 ...
3
votes
0answers
104 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 ...
0
votes
0answers
29 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 ...
2
votes
1answer
108 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 - ...
0
votes
2answers
176 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 ...
1
vote
0answers
22 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 ...
3
votes
2answers
125 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 ...
0
votes
2answers
44 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 ...