39
votes
5answers
6k views

Why does a candle blow out when we blow on it? Our breath is 16% oxygen and only 4% CO2

Don't say that a layer of carbon dioxide covers the flame, because our breath has more oxygen than carbon dioxide. Also, our breath does not cool the flame as it is itself warm. So what is happening ...
10
votes
4answers
475 views

Why does my door shut faster when the window is open?

I've noticed that if I shut my door when the window is open in a room, the door will tend to shut faster. If I shut the door when the window is closed with a normal force it will not fully close as if ...
1
vote
1answer
129 views

Will the “Vacuum Wine Saver” suck the bubbles out of Champagne?

The "Vacuum Wine Saver" comes with the following "warning": Not for sparkling wines Intuitively and naively, I imagine that the bubbles (or the "bubble-potential"—my made-up terminology) will be ...
1
vote
2answers
252 views

The Soda Can and air pressure experiment

Yesterday, I made an experiment. I filled an empty (but contains air) soda can with a little bit of water. Then I turn on fire at the sides of the soda can so that the water starts boiling. Next, I ...
5
votes
2answers
765 views

Why does deodorant always feel cold?

We all use deodorant and they always feel cold, why is that? Is it because it is liquid inside the bottle and a gas when it is released?
6
votes
1answer
327 views

How to make the bubbles in my soda drink last longer?

I would like to make the bubbles in my soda drink last longer. For example, one good thing to do is to keep the bottle shut when you don't drink. But what else I can do? Should I try to minimize the ...
5
votes
1answer
163 views

Weather forecasting with coffee bubbles

The other day I saw this life-hack: And I was wondering how true it is. First of all, I always thought(listening to weather forecasts) that low-pressure atmosphere is what correlates with rain; ...
5
votes
3answers
365 views

A book sits on a table. What is the net force of air pressure?

An elementary problem asks, A book is at rest on a table top. In what direction is the net force of air pressure on the book? Is this a meaningful question, and if so, what's the answer? If ...
2
votes
1answer
114 views

Balloon Inflation

I am planning to use an air compressor to inflate a rubber balloon. I need to size the compressor for inflating the balloon, but for sizing the compressor I need the pressure required to inflate the ...
10
votes
2answers
488 views

Movie airplanes and suction

Having watched a recent action movie (with zombies in it) I wondered whether the suction from a hole in the airplane's hull would really be able to rip out luggage, persons and even seating benches. ...
-1
votes
5answers
3k views

Is it possible to generate electricity using a water tower?

Is it possible to build a water tower that will provide enough pressure to run an electricity generator? A water pump can be used to send water up to the tower. The water pump can be powered by solar ...
1
vote
2answers
158 views

Can random constructive interference with sound waves cause damage?

Any two sound waves have a random chance to constructively interfere with each other at a given spot and this will cause an increase or decrease in pressure. So is it possible that a large number of ...
4
votes
1answer
128 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 ...
3
votes
1answer
148 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 ...
6
votes
1answer
142 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 ...
10
votes
2answers
264 views

What if the lid of a pressure cooker was suddenly released?

My dad and I have tried to calculate the strength of the explosion if the lid was suddenly freed. We took some measures: Lid mass: $0.7 \textrm{kg}$ Lid surface: $0.415 \textrm{m}^2$ Internal ...
3
votes
1answer
238 views

Why does the bubbling of a soda bottle pulsate?

If I take a bottle of carbonated water and open the cap slightly to allow the gas to escape, there will be a sudden rush of bubbles foaming to the top of the liquid for a few seconds, then a partial ...
9
votes
5answers
2k views

Why does my refrigerator door resist opening?

After closing my refrigerator's door I noticed that it's much harder to reopen it immediately, as if there's an underpressure. Only after a minute or so it opens normally. How can this be explained?
5
votes
3answers
643 views

Get an intuition for pressure values

I am currently working with pressure differences in the milibar range. However I do not have a good feeling for pressure differences. In every day life: Where does a pressure of say 100 mbar over ...
8
votes
4answers
8k views

Why will crushing a partially empty 2-liter bottle keep the soda more fizzy?

One of the curses of 2-liter bottles is that when carbonated beverages are stored in them for long periods (i.e. days between drinks) at least the last liter ends up being flat. However, if after ...