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

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What make us fall when we move on ice? [duplicate]

This is a common phenomenon and most of the people have encountered this while moving on ice:falling down! Why does this occur? According to me, it is due to lack of static friction. But why will it ...
3
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1answer
36 views

What is the best angle to see water

Sometimes when I clean my house, I miss some of the water since it seems invisible, but when I stand in different angle from the water I can see it clearly, whereas some angles offer partial ...
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44 views

Why can't we reach the ends of rainbow?

Rainbows are spectacular things. But I imagine why we can't reach to the ends of rainbows. Do rainbows have no ends ? If so, why can't we reach at them? If you go closer,they will go further. Why?
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2answers
165 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 ...
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24 views

Magnetic field of magnetic screwdriver?

I wanted to know what is the typical strength of the magnetic field generated by the tip of a magnetic screwdriver, but couldn't find it anywhere on the manufacturers' webpages. So I was wondering, ...
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1answer
362 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 ...
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3answers
4k views

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

Most of the time I mixed different nuts in a bowl, I observed that the big Brazil nuts were always at top while the small peanuts settled near the base. No matter how you take it, if the big nuts are ...
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18 views

Objective visual reality [on hold]

All living organisms (humans, animals, insects) sees the world differently (subjectively) through their own different visual systems. So how does the world looks like objectively (independently from ...
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2answers
326 views

Why is it so hard to mix spaghetti with meatballs?

When I cook spaghetti with a sauce that includes meatballs or chopped vegetables, those stay in chunks and won't get uniformly mixed in the pasta. Is there a simple reason for that? Has it been ...
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3answers
327 views

Why do I hear the telephone ring through grandpa’s hearing aid before the actual phone rings?

I was sitting next to my grandpa (Tato), who wears a hearing aid, on the couch. I’ve noticed that when the landline telephone rings I actually hear the phone ring through his hearing aid (less than ...
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2answers
2k views

Why does a dish cloth absorb liquid better when it is damp?

Take a really dry dish cloth and try to wipe up some liquid you spilled on the kitchen counter. I will take up only so much of the liquid. Then try it with a damp cloth (or a wring out a wet one). It ...
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479 views

Benefits of rear spoiler in cars

What would be the benefits of rear spoilers in cars, like this one:
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3answers
4k views

Is this really a golden ratio spiral?

In this blog post, I found this picture: Does the water really form golden ratio spiral in such cases? Or is the photo just a provocative example, without physics grounds for claims about ...
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1answer
24 views

How big are soluted salts in drinking water?

I have just seen the TED talk Michael Pritchard: How to make filthy water drinkable where a device called LifeSaver bottle that filters particles that are bigger than 15nm out of water. I have heard ...
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2answers
2k 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 ...
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2answers
515 views

Does the mass of a car frame has any effect on its horsepower?

I want to know whether decreasing the mass of the frame of a car will increase its horsepower. From what I understand horsepower is a measure of the car's ability to transport load, and decreasing the ...
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1answer
78 views

Is it possible that a battery goes flat faster in a cold environment?

I own an old iPod Classic with original lithium-ion polymer battery and I use it primarily while running. Recently I discovered that when a temperature outside is low, usually below 5 C degrees, the ...
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2answers
149 views

Glass tends to be cold?

In winter, our glass window serves as a separator of coldness outside and warmth inside our room. We know that the window feels cold when we touch it. Since the air temperature is different in ...
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1answer
110 views

Why there is a time gap between the news presenter and the field reporter?

This one has been in my mind for years, but I simply can not find any reason for this event. The Situation Imagine yourself sitting in the living room while watching television. It's 9 p.m and the ...
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0answers
53 views

Definition of spatial and temporal coherence in QM?

It is often said that lasers are spatially and temporally coherent. Is there a simple definition of spatial and temporal coherence in the language of quantum mechanics? More specifically, can these be ...
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2answers
112 views

Can you punch a hole in an A4 sheet of paper with your hand?

The Heading says it all. But let me explain it a little further. Suppose you hang a sheet of paper (A4 size), from one end leaving the other end free. Now practically it seems impossible to punch a ...
6
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1answer
249 views

Where is the “event horizon” on a basketball hoop?

I'm watching a lot of basketball this month. A common event is the ball going part way into the hoop and then coming out again. Announcers sometimes claim that the ball was "halfway through" when it ...
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2answers
88 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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2answers
4k views

Why does my wooden door disperse light into a rainbow color spectrum?

On a clear morning, light comes through this window (viewed from the inside) It then hits the door on the opposite side (so viewing from the outside the door straight on the other side) There is ...
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0answers
105 views

Why is cooling much harder than heating?

I'm trying to invent a distillation apparatus that runs solely on electricity. Suddenly, I realized that cooling things is really hard, while heating them up is so easy. Actually, it seems that there ...
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1answer
44 views

Why do bubble wands have ridges?

The bubble wands supplied with children's bubble mixtures seem to fairly universally have a set of ridges around the hole used to create bubbles - for example, see the circle in the upper right of ...
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2answers
113 views

Why does cling film (Saran Wrap) cling better to surfaces which are wet or damp than dry?

The product we know in Canada as Saran Wrap is a clear plastic film (no idea of the chemical formulation, believe it to be polyethelene). Among its uses are to cover a dish or bowl. If the hard ...
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6answers
2k 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 ...
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2answers
261 views

How do I figure out the momentum of a water balloon when it reaches the person I am throwing it at?

Recently an experiment was performed in which myself and a partner filled a water balloon and threw it back and forth at each other without breaking it. We gradually increased the distance at which it ...
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3answers
765 views

Why is the sky dark at night? [duplicate]

The question is the well-known Olbers' paradox: If there are so many/infinite stars, in every direction, why is it dark at night? Where goes all the light we don't see? Discussing with a friend ...
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1answer
233 views

Why is wet paper transparent? [duplicate]

When paper get wet, it becomes transparent. How does this happen? Is it because of refraction, or bcause water extends the space between molecules that consist of the paper? I have no clue.
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1answer
42 views

Cold welding of a metallic surface

I have heard of cold welding, it's said that it's only possible if the surface is very clean. Can cold welding be accomplished by shearing a metal object and then immediately touching the newly ...
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1answer
232 views

Steam above meal

When I fry something on the pan and the fire is big and intensive (the flame over the pan), there is no stean above the pan or just a little. But when I turn off the fire, suddenly the steam appears, ...
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255 views

How does train back draft work

Quoting platforms and stations : Fast trains can create a vacuum called a ‘back draft’ that can blow you over or suck you under a train. How does that work ? I thought that the volume of air ...
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1answer
48 views

Modeling wall's behaviour

Sorry if the quesiton is inconvenient, but I judged the physics forum would be the best place to go. My house is divided in two parts by a wall, and there's some tree pushing it, so the wall is about ...
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6answers
3k views

The best way in which a man can pull a train

I have chosen this example as a paradoxical limit, but my question really regards the optimization, distribution and outcome of force when you try to pull a weight: how can you optimize your ...
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7answers
1k 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 ...
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7answers
3k 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, ...
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1answer
47 views

Will a tug-of-war battle damage my climbing rope

I plan to organize a big tug-of-war with a climbing rope (70m long) with 50-60 adults. I know the climbing rope is elastic. The rope resistance is 9 kN when a chock occurs. Will the rope breaks or ...
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2answers
78 views

Which dumplings will be more salty?

There are two identical pots filled with different amounts of water (one has more water, the other one has less). The same amount of salt has been poured to each pot. The same amount of dumplings has ...
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2answers
106 views

How can you accurately determine your own mass?

I'm trying to figure out whether it is possible for an individual to accurately determine his/her own mass, to within 100g, using equipment that is readily accessible or can be purchased at a ...
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7answers
9k views

Why does hot water clean better than cold water?

I had a left over coffee cup this morning, and I tried to wash it out. I realized I always instinctively use hot water to clean things, as it seems to work better. A Google search showed that other ...
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2answers
588 views

Punching - Force or Momentum?

If I want to punch a person inflicting maximum damage, what do I need to care about? My force of punching, i.e, do I need more acceleration? Or do I need momentum, i.e my velocity for punching?
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2answers
96 views

Add weight in front or behind the moving wheel?

Consider a wheel with bearing and axle bar rolling on level ground. If I want to help the wheel continue moving longer(or faster speed), should I add weight by moving the rider body in front or ...
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2answers
81 views

What makes a material adhesive (or sticky)?

I currently have a bandage on my arm that isn't sticking to me but definitely sticks to itself. It brought up the question: What makes a material sticky? What's happening on the molecular level? Why ...
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2answers
94 views

Does distance traveled by a vehicle after its engine has been switched off depend on its mass at all?

A vehicle moving with some velocity on a rough horizontal road finally comes to rest after its engine has been turned off. Intuitively, it seems a vehicle with greater mass would stop first because it ...
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1answer
84 views

Why is a white cloud formed in the hot water from the pot when salt is added?

Why is a white cloud is formed in the hot water from the pot when salt (NaCl) is added?
88
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7answers
6k 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 ...
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2answers
790 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?
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1answer
182 views

How many molecules rub off when I press a key?

I have a lot of questions below but my overarching questions are: Do surfaces rubbing lightly together always strip molecules off of each other? and How can we model that? Clearly the answer to the ...