Questions tagged [everyday-life]

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

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Why do cool things warm up slower than hot things cool down?

Why do cool things warm up slower than hot things cool down? My guess is it has to do with Newton's Law of Cooling since cool things are closer in temperature to the ambient air than hot things are, ...
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3answers
92 views

How do window blinds work?

How do window blinds help to reduce the temperature in a room? On the one hand, I know that drawing the blinds helps my room to stay cool in the summer. On the other hand, just as much sunlight is ...
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What is the main mechanism for induction heaters (cookers)?

I thought that induction heaters (as used in cooking) relied on Joule heating losses due to Eddy currents induced by an oscillating magnetic field, produced by an inductor through which AC runs ...
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Why is dry soil hydrophobic? Bad gardener paradox

When I forget to water my plants, and their soil becomes very dry, during the next watering I can see that the soil becomes hydrophobic. I can even see pockets of air between the repelled blob of ...
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Water freezing pressures

So say we have two bottles that are each a liter in size, exactly the same. Let's not get into thickness or chemical makeup of the plastic that can be considered insulation. They both have caps on. ...
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How much of a gravitational change would be noticeable? [closed]

Assuming we could turn the gravitational constant in a gym up or down on a dial, what percent would the change need to be before it became noticeable?
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Why does wrapping aluminium foil around my food help it keep warm, even though aluminium is a good conductor?

Aluminium being such a good conductor, how is it possible that it is helping me keep my food warm ?? Because ultimately it should conduct the heat that is inside to the outside for exchange and ...
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2answers
68 views

Can we distinguish how an object was warmed up?

Suppose I warm a glass of water up to 50°C in the microwave. In the other hand, I warm up exactly the same amount of water to the same temperature, but in the oven. In this situation I would have two ...
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28 views

Warm or cold air

Which air can be used to dry out food or clothes? Warm or cold air? I've read that keeping food in the fridge makes it dry out. Blowing hot air to the hair also dries the hair out. I'm confused.
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1answer
66 views

Why does an aluminum foil spark inside a microwave oven? [duplicate]

I did an experiment today. I put an aluminum foil inside the microwave oven thinking that nothing would happen. But contrary to my expectations it started sparking badly. I looked for answers on the ...
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2answers
59 views

Why do water tend to rotate when draining?

Whenever I wash the dishes, I realize that water always tend to acquire some kind of rotation with respect to the axis passing through the hole of drain. I'm not sure if my observations account for ...
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Why is it that when a chalk board gets cleaned, the area that used to have chalk is the cleanest?

Why is it that when you erase a chalk board, the area where the chalk used to be becomes the cleanest? By that I mean that when you erase a chalk drawing, the board gets smeared with chalk dust, but ...
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1answer
74 views

How does my body temperature stay lower than ambient air temperature if it goes over 37°C?

I know it's because of sweat, but why should the sweat over my skin get heat from the body, cooling it under the ambient temperature, instead of getting it from the hotter air all around me? If I ...
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1answer
47 views

Opening a bottle cap

How exactly is a bottle cap opened/closed? To open/close one, it needs to be rotated and simultaneously translated upwards/downwards for it to move up/down its thread and not be translated right or ...
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1answer
57 views

Why a drop of water acquires the shape of circle while getting absorbed on a bed sheet?

I am quite amazed by this observation as I couldn't prove it or intuitively have a correct reasoning for the circular geometry of the water drop which it acquires while getting absorbed on a bed sheet....
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1answer
32 views

Color dispersion at the edge of a slanted mirror

When I look at the edge of a slanted mirror it looks like its affected by color dispersion which you can see by Image 1 but, when it reflects off the flat part of the mirror it looks normal, Image 2. ...
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How does a mister form the mist?

A mister exploits pressure difference to pull water up from the reservoir and through the outlet (Ref:https://www.explainthatstuff.com/aerosolcans.html )But what converts the water in bulk liquid form ...
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2answers
84 views

X-rays / Gamma rays “oven” vs microwave oven

Let's imagine a seller scammed you and sold you a Gamma rays / X-rays "oven" instead of a common microwave oven. The power consumption would be the same as a common microwave oven, i.e. about 1 kW, ...
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4answers
445 views

Why we can't jump without bending our knees?

I observed it while trying to jump from my bed with my knees straightened and I failed to do it. I want to ask whether it is with all of us our it may be a medical issue with me? Why we can't jump ...
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1answer
45 views

Why does my rear window defogger remove rain?

I've noticed this before and still don't have a picture, but... Today it was lightly raining in the morning. As always, I turned on the rear defogger. I do this because I have noticed it clears the ...
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1answer
26 views

Sound made by trapped water

When I run water in my bathroom sink and then put the plug in whilst there is still some water left in the basin, there is a high pitch moaning or screeching noise made by my adding the plug. What ...
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2answers
29 views

Why texture of an object depends on the amount of light it reflects?

The darker an object, the less visible is it's texture: texture of blackboard is visible because it reflects 7% of light; texture of an asphalt road is visible because it reflects 4% of light; an ...
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1answer
48 views

Tearing paper by creasing/folding

Why does folding/creasing loosen the fibre-fibre bonding in paper? Creasing makes tearing paper easier because it weakens the fibre-fibre bonds or makes the strong fibres easier to tear, it is said. ...
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2answers
73 views

If black color body absorbs all colors, why spectrum of light appears on black shoe?

Few days back in a 10 grade school practical, we were shown the dispersion of light by a prism to create spectrum. Then we went into the open sun and performed it under a linear building roof and ...
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1answer
97 views

How do knife blades become dull?

Knives are normally used to cut softer objects. So the edge of the knifes blade is harder than the substance it cuts through. A blades geometry is more complex, but let's simplify it to the blade ...
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1answer
112 views

Why is pizza soggy after microwaving?

Compared to when heated over fire, pizza is soggy when heated in a microwave oven. I want to know why this is. So far I’ve just learnt that microwaves in ovens are of a specific frequency of ...
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3answers
338 views

Why choosing for prime numbers eliminates vibration?

I have read that the spokes of a car wheel are usually five because, besides other substantial reasons, five being a prime number helps to reduce vibrations. The same also happens with the numbers of ...
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Why do the tyres of the vehicles burst during summer?

The explanation of most is -According to Charles' law if the temperature increases volume should also increase and hence the tires burst. But it is also that if volume increases pressure decreases (...
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1answer
43 views

Why does a cup on water layer create suction?

When I place a cup upside down on a layer of water, say a wet table, and I then try to lift the cup up, I can feel some resistance. So the cup is acting like a suction cup. However the difference is ...
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2answers
45 views

How can the motion of the brain within the skull be stopped at the moment of impact? [closed]

How can the motion of the brain within the skull be stopped or controlled at the moment an object with velocity comes in contact with it. What type of a system would this require?
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Predicting the effect of a power outage on the temperature in my fridge

I have a commercial fridge, without a freezer. It is vertical fridge with one glass door. We have medications we want to keep below 8°C. Most medication tolerate a slight T elevation without problem. ...
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2answers
62 views

Are there any crystallographic effects we can see in the reflection of visible light from metal surfaces?

I started thinking about this in a discussion in comments. One can start by thinking of the reflection of visible light by most metals as similar to the reflection of radio waves in that it's an ...
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54 views

Why does rubbing a coin on steel make vending machines accept it?

I have seen people scratching their coin against the vending machine in order to make it likelier to accept it. Conceivably, this habit might be due to some confirmation bias and lacking any rational ...
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1answer
52 views

Why light travels through shortest path during refraction?

I know in order to compensate with change in speed but how does Light actually know which path is less dense or more dense?
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1answer
50 views

Movement of bubbles in a cup of tea

Why is it that when I try to scoop bubbles out from the surface of a cup of tea, they always slip off the spoon even if some of the tea does not?
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1answer
72 views

How has the Earth's air pressure varied over geological time scales?

It is estimated that the Earth is losing about $5 \times 10^7 kg$ per year. Most of it due to hydrogen loss. I suppose this has an impact on the pressure of the atmosphere in general. Thus, I am ...
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25 views

Aerodynamics of a bed sheet

Given the mass of a bed sheet and its area, is there any way of determining the probability of it landing "perfectly" when it is jerked up on the bed (by jerk i mean when you are making your bed and ...
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39 views

What is the lift coefficient of human body?

Assuming we can change angle of attack by changing our hands orientation what is the maximum aerodynamic lift coefficient of human body?
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Increase in temperature after an unexpected rain during summer

Why we feel an increase in temperature of atmosphere than usual after an unexpected rain during summer? Usually the raining should have to reduce the temperature of atmosphere.
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1answer
27 views

Fastest way heat water (or some other liquid or material)

If I want to heat lets say, 1 liter of water - would it be faster if I heat half a liter, and then another half a liter? or slower? my guess is that its not equal (lets assume that the time it takes ...
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2answers
87 views

Why are fridge doors magnetic?

Why do fridge magnets stick to fridges? What purpose does a magnet have in a fridge? Why do the magnets stick so well to the fridge doors but not so well to keys or nails?
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Gravity “sorting” and French Press coffee

I have read about the Earth's sorting of different-sized grains of sand and such. Larger particles are supposed to fall through water faster. I've seen it demonstrated before and have full faith. But ...
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1answer
142 views

I was wondering if the mass of an object can be measured by the effect it has on a body of water if it was dropped from a certain height? [duplicate]

The question: Height of Water 'Splashing' asks about the height of the splash when an object is dropped into water, but there are other parameters that can depend on the mass and velocity of ...
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3answers
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Life physics: falling objects

I've started wondering for a while WHY we experience so much damage when we hit a ground after a free fall? What forces are responsible for that? After some thinking I concluded that it has to do ...
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3answers
98 views

Why cars have transmission gears? [closed]

Cars need transmission to efficiently vary the speed of the wheels and this due to the fact that the internal combustion engines have a very limited torque band. What I don't understand is why ...
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1answer
76 views

Grooves on water tank

Why are there grooves on almost every water tank? Just typing water tank in Google images would reveal what I am talking about. And here is a sample picture! I think it would mostly be regarding ...
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1answer
46 views

What physics describe the way a waiter/ waitress is balancing his/her serving tray?

A waitress in order to balance his/her tray is continuously moving this tray up and down. Similarly if you want to balance a pencil by its tip on your hand, you move your hand up and down. Does ...
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1answer
54 views

How two cars are getting at the same point of the road (obstacle, cyclist, another car parked on a small part of the road) in the same time? [closed]

You have an ordinary road, two ways. You are driving on the right part of the road and you see a person walking on the same part 400m away, you have to slow down or to accelerate because from the ...
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1answer
338 views

How do car rear-view mirrors work? [closed]

I wonder, how does a car rear-view mirror work? When there is a car behind me with high-beam, all I do is flip a tong at the bottom of the mirror to relax the lights! Are there two mirrors in it, ...
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1answer
53 views

Why do the black balls floating on top of the water surface form lattice strctures?

The phenomenon I'm asking about can be seen in this veritusium video. The balls were just dumped in randomly, and they are buffeted by wind and currents, so how do they settle into clean lattice-like ...