Millions saw the apple fall, But Newton asked why.
The Vapor Cone.
A vapor cone, also known as shock collar or shock egg, is a visible cloud of condensed water which can sometimes form around an object. A vapor cone is typically observed as an aircraft, or object, flying at Transonic speeds. ( slightly slower than the speed of sound)
The Pressure – Temperature dependence.
As the aircraft approaches the speed of sound, the air pressure around the object drops, and thereby the air temperature drops. If the temperature drops below the dew point, water in the atmosphere condenses to form a cloud in the shape of the shockwave.
Red Bull Stratos and the Vapor Cone.
Remember that epic jump where Felix Baumgartner, as a part of the Red Bull Stratos project broke the sound barrier ( reached Mach 1.25 ) during his descent? But why weren’t vapor cones seen around Felix’s body? Or were they?
Vapor cones are formed only near the ground, where plenty of wet air persists. But when Felix broke the sound barrier, there was no wet air that surrounded him that would enable the formation of Vapor cones.
“Mommy, Why do Bottles cry?”. I was travelling in the bus the other day and a five-year-old asked this subtle question to her mother. Although I could not hear the mother’s response, I was still startled! Somewhere between making a transition from child to teen, we seem to have lost the enthusiasm to ask questions. However silly it might be! Where did it go? ( A food for thought )
Let’s say you place a cold water bottle on the table. There are millions of water droplets present in the air surrounding the bottle and they are at room temperature.
When these water molecules which are at a higher temperature come near to the cold water bottle, they lose out the heat/energy that they possess and thus make a phase change from a gas to liquid.
This process is known as Condensation. The liquid water which gets condensed is the ‘tears’ or ‘sweat’ that you observe on the bottle.
Condensation is also the reason for the formation of dew( Water droplets) on leaves and other exposed objects in the morning or evening.
Refraction Demonstrations- Does it ever get old?
There have been a lot of posts on Fuck Yeah Physics! on Refraction. But yet, Refraction still does not fail to amuse me.
Water is blue if you are talking about the water present in oceans, lakes and even your bathtub!
This is because red, orange and yellow (long wavelength light) are absorbed more strongly by water than is blue (short wavelength light). So when white light from the sun enters the ocean, it is mostly the blue that gets returned.
The hue of the sky (Azure) also contributes to the color of water.
The above phenomenon is predominant only when the depth of the water is about 1 meter.
This is why if you pour water into glass, it does not appear blue. It is colorless!
The color of water can also be altered by the particles present in water. For instance, presence of algae in water gives water a greenish color.
While high concentrations of dissolved lime gives it a torquoise color.
In extreme scenarios, water is seen to be in red and black in color.
So, what is the color of water you ask ? For all intents and purposes for everyday conversation, considering the magnitude of water present in Oceans, Seas, and Lakes, I guess it is safe to consider the color of water, as Blue!
Cutting a drop of water using a Superhydrophobic surface and a knife.
Superhydrophobic surface is one which highly water repelling.
Total Internal Reflection.
Total internal reflection is a phenomenon which occurs when a propagating wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface.
This occurs when the incident angle is more than the critical angle and the refractive index is lower on the other side of the boundary ( like from water to air ).
Unraveling the physics.
The photograph is an amazing illustration of the centrifugal force.
Do you remember those times when you get squashed on to one side while trying to maneuver a tight turn in your car? The force that is pushing you out is known as centrifugal force.
Let’s up the ante. Imagine you are piloting an aircraft and you are pulling an inside loop i.e
It is the same scenario that you experience in your car with the axis of rotation being vertical.( In the former it was horizontal ).
Our friend, the centrifugal force would be squashing you to your seat. Water also has to comply with the centrifugal force and as a result gets squashed towards the cup.
Voila! The physics of pouring water into a cup when you are upside down :).
EDIT: To pull this off, the centrifugal force has to be more that the force of gravity else the water would fall the other way around.
Much like water, the bodily fluids also gets squashed to the bottom. This reduces blood flow to the brain, which is why people often pass out!