集聚第一资源 激发第一动力（融两会·讲述）
百度 而此次冰下搜救，两名潜水员要找到一个预先设定好的“被困者”，在冰下确认同伴后，潜水员以水绳为圆心，利用线轴进行圆形搜索，绕圆一周再放一米线轴继续搜索，依次反复。
Concerns the application of the laws of physics to analyze common situations encountered in everyday life.
2,307 questions
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Does heat pump work more efficiently than electric heater? [duplicate]
My question comes from another very simple question: If I want to heat my house by a electric heater or a heat pump driven by electricity, which cost me more? As far as I've learned, the efficiency of ...
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Do water heaters create visible ripples in the surrounding water? [closed]
I have an aquarium and around the heater there are ripples in the water.
Do aquarium heaters create ripples in the surrounding water?
If so, why does this happen?
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Why do shadows appear to merge at a specific distance? [closed]
I've observed an interesting phenomenon with shadows that I'm hoping someone can explain. When two distinct shadows are cast near each other by separate, parallel light sources (or even a single ...
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If I point a telescope at a mirror reflecting the Moon, can I see the same amount of detail?
I'm watching Better Call Saul and at some point a character points his binoculars at a mirror to check what's going on behind him. I never noticed that, at least in principle, this should work fine (a ...
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Why is grid-wide battery storage capacity measured in units of power instead of energy?
A battery stores energy, not power. It would not make any sense for something to "store power", because power is not a conserved quantity.
Therefore, the energy storage capacity of an ...
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Why are there shadows surrounding these underwater lights?
I took this picture of a water feature on campus at Caltech:
The lamps at the bottom of this pool have large, circular shadows surrounding them, but there are also bright rings of light surrounding ...
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Is this infinite transportation? [duplicate]
I was surfing across internet and landed at a post on Twitter, suggesting this design as a form of infinite transportation.
So, I decided to ask it on Physics Stack exchange, to find out if it is ...
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Why do traffic jams happen even on a highway?
I was surprised to find myself in a traffic jam on a highway (it's a densely populated city). If we think of vehicles on a highway as particles flowing in a pipe, when the inflow exceeds outflow the ...
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Why is it easier to insert a straw into a bubble tea bottle when one end is blocked? [closed]
The usual standard answer is that because of the air pressure:
By sealing one end, you create a slight internal pressure that
counteracts the external pressure applied during insertion. This
further ...
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Is there a critical number density of snowflakes after which snow becomes white?
If I understand it correctly, snow is opaque and white because you have much more reflective surfaces than transmissive surfaces. An ice brick on the other hand, has much lesser air-ice boundaries ...
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Sun turns blue when seen through a crossed polariser/analyser
It was sunset, and we were looking at the sun through our polariser/analyser setup. When the angle between P and A was zero, the sunset looked normal (albeit with an expected reduction in brightness).
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Why does a mosquito net block the breeze even though its mostly porous?
When my window is fully open, I can feel the breeze from outside. But when I put on my mosquito net, the breeze gets blocked almost completely. Why does mosquito net block the breeze, even though its ...
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How does the train window add another colored stripe to the Adidas logo?
While traveling on the underground today, I noticed something funny. In a tunnel, I could see the reflection of my sports bag in the train window.
However, the three white stripes on my bag looked way ...
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X-effect from Variable ND Filter photography
I’m trying to understand what’s happening when using a variable ND filter in photography.
A variable ND filter is placed in front of the lens to control the amount of light that reaches the sensor. It ...
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At what depth does it become impossible to urinate? (Because of water pressure)
And what would happen if you tried?
I'm also curious if the answer varies between the sexes.
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