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.
2
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1answer
66 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 ...
12
votes
5answers
1k views
Why Won't a Tight Cable Ever Be Fully Straight?
I posted this picture of someone on a zipline on Facebook.
One of my friends saw it and asked this question, so he could try to calculate the speed at which someone on the zipline would be going ...
4
votes
1answer
44 views
What is the minimum pressure difference for your ears to pop?
I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
4
votes
1answer
76 views
How does my hand amplify an FM radio signal?
I have a gizmo that broadcasts an FM radio signal from my phone's headphone socket to my car's radio antenna.
Sometimes, there's another station on the same frequency with a stronger signal and my ...
5
votes
3answers
218 views
How can I determine the coefficient $k$ in $ \dfrac{dT}{dt} = -k(T - 100 \mathrm{^\circ C}) $?
I recently spend some time on cooking and I'm curious about the time evolution of the temperature of the water. I did some experiment and the temperature is of the form
$$ T = 100 \mathrm{^\circ C} + ...
4
votes
3answers
207 views
Why don't electric workers get electrocuted when only touching one wire? [duplicate]
I know that when electricians work on the poles on the streets, if they only touch one wire at a time they will be fine. However, from my understanding, the negative wire is connected to a large ...
0
votes
2answers
51 views
Does more reflective aluminum foil make a room cooler compared to less reflective foil?
Aluminum foil is said to be not absorbing light at all.
It reflects light. So, does it mean that a more shiny aluminum foil will reflect more light and thus make the room more cooler as compared to ...
13
votes
1answer
193 views
Modelling the movement and jumps of a chalk while drawing a dashed line on a blackboard
You probably know that if you try to draw a line using a piece of chalk on a blackboard , under some conditions (for example, $\alpha<\frac{\pi}{2}$ in the picture below) you will have a dashed ...
1
vote
1answer
34 views
Why do lumps of sugar break more easily when blowing in it?
My question is simple, when you have a small lump of sugar, it's hard to break it with your bare hands, but when you blow in it, it appears to be more easy. (it's a piece of advice i learned for my ...
22
votes
6answers
2k views
How do whisky stones keep your drink cold?
From a discussion in the DMZ (security stack exchange's chat room - a place where food and drink are important topics) we began to question the difference between how ice and whisky stones work to ...
2
votes
2answers
149 views
Using Electrostatic Force to Repel Dust From an Object
I have two 4,000V, 2.5mA, DC power supplies and am attempting to use them in such a way to cause a 6x4x1-inch ABS plastic object to repel dust from the ambient air and prevent this dust from settling ...
2
votes
0answers
50 views
Seashell occurrance
Sometimes, sea shells accumulate on the sea shore, but sometimes they will instead be dragged back out to sea. What are the main physical factors that determine which of these things will happen?
0
votes
2answers
276 views
Center of gravity of vehicle and vehicle performance
I am interested to know how does CG of vehicle plays role in the Fuel economy and the vehicle performance. Does CG of vehicle has anything to do while accelerating of your vehicle. I am a student, ...
4
votes
0answers
139 views
Why is it hard to breathe when cycling against the wind?
Sometimes when I bicycle against hard wind, I find it difficult to breathe. Others I have discussed it with have also noticed this effect.
A possible related phenomenon that I heard from an ...
19
votes
3answers
362 views
How much information about the scale of a waterfall can be obtained from its sound?
Is it possible to constrain the height, volume flow, or distance of a waterfall from the quantitative analysis of a high-quality recording of its sound?
As an aside, the simulated sounds of fluid ...
12
votes
6answers
858 views
Does an empty refrigerator require more power to stay cold than a full one?
Given that everything else is equal (model of fridge, temperature settings, external temperature, altitude), over a given duration of having the door closed, does it require more electricity to cool ...
4
votes
3answers
148 views
Does more rain strike a vehicle while moving or while stopped (or neither)? [duplicate]
Assume there is a rainstorm, and the rain falling over the entire subject area is perfectly, uniformly distributed. Now assume there are two identical cars in this area. One is standing still, and ...
3
votes
1answer
61 views
Does tapping at the side of a bottle prevent shaken soda from bubbling over?
Anecdotal evidence has it that a bottle of soda that was heavily shaken will not bubble over if tapped at the side multiple times.
Yet I wonder: Has the tapping really any effect? Or could it be that ...
2
votes
4answers
77 views
Would a phone move upon vibration in a completely uniform situation?
I was sitting down yesterday and saw my phone vibrate on a side, and it moved about a centimetre per vibration.
I wondered why it moves, and thought perhaps that the side it was on had a slight ...
8
votes
3answers
523 views
How hot is the water in the pot?
Question: How hot is the water in the pot? More precisely speaking, how can I get a temperature of the water as a function of time a priori?
Background & My attempt: Recently I started spend ...
9
votes
8answers
2k views
Why do ice cubes come out easier from top trays?
This is my "hey, I've noticed that too!" question for the week. If you stack two plastic ice cube trays with water in them in a freezer, the resulting ice cubes in the top tray will usually come out ...
16
votes
2answers
237 views
Stripeless cleaning of windows
Cross post: http://chemistry.stackexchange.com/q/4377/22
Last week I was discussing with a friend how we thought the stripeless cleaning of windows is achieved when using a cleaner like Windex ...
1
vote
1answer
53 views
Reducing deposition on power supply wires
From my house there are two wires, i.e. a live and a ground wire which are placed on the power supply lines by a hook. They are not tightly jointed because of some reasons. These two wires are also in ...
3
votes
1answer
74 views
What pressure or tension occurs in a glass jar when I pour boiling water inside?
Sometimes it happens that when you pour a boiling water into a glass jar, it cracks. Since glass is very hard material and resilient to pressure, the tension must be very high. Is it possible to ...
7
votes
1answer
105 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. ...
0
votes
0answers
99 views
Spontaneous explosion of a bottle containing alcohol and milk [closed]
Cross-posted at Chemistry SE
A friend of mine gave me a bottle of home-made liquor which is a concoction of pure alcohol and sweetened milk. I accepted his gift happily and then I put the bottle ...
1
vote
2answers
115 views
What will happen if we place salt water on a induction cooker?
As we know that induction cooker works on the principal of induction of current in a conducting plate. So I just wanted to know what will happen if we place salt water in a plastic container on the ...
3
votes
4answers
270 views
Why does higher acceleration minimize a car's fuel consumption?
I generally try to optimize my car's fuel consumption when driving, using my car's real-time MPG gauge and average-trip MPG indicator.
Until recently, I believed the slower the acceleration, the ...
1
vote
1answer
85 views
Why does tea rises in the pot but water don't?
I was wondering when I boil water in a pot it only shakes too much while boiling. But I could not figure out why tea rises in the pot when we boil it. it is also a liquid but it starts rising up till ...
5
votes
4answers
166 views
Can a balloon be used as an anchor point for a pulley?
For a physics/ engineering contest, I want to use a large balloon as an anchor point for a pulley. This would allow me to raise and drop masses.
However, in testing, when I pull on the pulley the ...
2
votes
3answers
1k views
How much energy was consumed when we turn on/off light?
My parents told me to turn off the light when I am not using it. But I remember my physics teacher told me that the action of turning on/off a light can cause huge energy. I am wondering how much is ...
2
votes
1answer
132 views
What is the cause of orange sky glow?
I live in the Netherlands and recently I have been seeing an orange glow in the sky at night, in the northwestern direction. What is the cause of this? And why is it in the northwestern direction (I ...
14
votes
11answers
1k views
Are there still 'everyday' phenomena unexplained by Physics? [closed]
There are two very famous quotes from German Nobel Laureate Albert Abraham Michelson that are remembered mainly for being extremely wrong (especially since he said them just before two major ...
2
votes
3answers
105 views
Flushing water-Is it related to Coriolis force? [duplicate]
There are videos and articles on the internet which demonstrate that water flows down a flush clockwise in Northern Hemisphere and anti-clockwise in Southern Hemisphere.
Here are a couple of links ...
1
vote
1answer
39 views
What controls the heating ability of steamers?
Pictured below is a standalone steamer used for foaming and heating milk for milk-based coffee drinks like cappuccinos and lattes. They can be filled with water up to the pressure relief incorporated ...
3
votes
1answer
66 views
What's the principle used in infant breath monitor devices?
Such a device consists of a sensor pad that is placed under a mattress:
What's the principle it uses to detect breathing?
13
votes
2answers
437 views
What causes ballpoint pens to write intermittently?
After a while, a ball point pen doesn't write very well anymore. It will write for a little distance, then leave a gap, then maybe write in little streaks, then maybe write properly again. It seems ...
4
votes
1answer
3k views
Why is my tupperware sealed after heating it up in the microwave?
I had a vegetable soup in a crystal tupperware and I put it in the microwave to heat it up.
The funny thing is that when I took it out, it was impossible to open it up. The lid is bent towards the ...
1
vote
1answer
113 views
Is my electric power cord creating magnetic field when coiled?
Simple question. But I was wondering, does my mac power cord create a magnetic field when its all coiled?
6
votes
6answers
533 views
When driving uphill why can't I reach a velocity that I would have been able to maintain if I started with it?
Consider these two situations when driving on a long straight road uphill:
Starting at a high velocity $v_h$, which the car is able to maintain.
Starting at a lower velocity $v_l$, and then trying ...
1
vote
1answer
323 views
What exactly is a Fluorescent lamp?
A fluorescent tube (home-based) works on the principle of discharge of electricity through gases, as far as I can tell (I don't know much about cathode rays or gas discharge)
What happens inside the ...
0
votes
0answers
61 views
On a Pilates reformer, how much resistance is from springs and how much from weight of user?
Here's picture of a Pilates Reformer machine: image
How much of the force required to move the carriage is based on the resistance of the springs, and how much is based on the weight of the user? ...
1
vote
1answer
112 views
why do lightbulbs sometimes unscrew by themselves?
I've seen some light fixtures which exhibit the behavior of lightbulbs gradually unscrewing by themselves.
2
votes
3answers
111 views
Why is there more steam when water is subject to less fire?
When I cook things, such as scallop and salmon, I found that the food may be more tender if I wait till the water boils (at 100 C) and immediately turn the fire lower so that the water is not bubbling ...
3
votes
1answer
293 views
What is the formula for the glug point?
When you pour water out of a bottle, normally you have a smooth stream. However, if you pour it too fast it glugs, which is to say, comes out in quantized bursts. What is the formula for calculating ...
9
votes
3answers
198 views
Does sound propagate further in freezing weather?
A few days ago I went for a walk in the evening. We're having winter with a little snow and freezing temperatures. We're in a quiet, shallow valley with a train station about 1km from us. I heard a ...
0
votes
1answer
125 views
Confused about fire?
Im confused about fire.
The way I see it :
Heat creates (kinetic) energy in mass and this creates stronger vibrations of atoms.
When those vibrations are strong enough the electrons interact ...
3
votes
4answers
340 views
Why does smoke go out the window of the car - and what if there's wind blowing instead of the car moving?
When driving a car while smoking with the window open (safety and legal issues aside), I've noticed that the smoke tends to go outside the window.
Why does the smoke go outside?
If the car is ...
20
votes
8answers
2k views
Why doesn't the bike fall if going with a high speed?
Why does the bike fall when its speed is very low or close to zero and is balanced when going with a high speed?
2
votes
3answers
174 views
Why does smoke go inside the car if the back door is open?
Inspired by another question I wanted to ask about phenomenon that I've experienced.
We had a van with separate trunk deprtment (similar looking one below) to transport things. But some of the things ...
