"Wisdom begins in wonder" – Socrates
Category: Physics
Filter Backwashing
09/25/25
“Why can we clean filters by pumping water backwards?”
Filters collect trapped material over time. Sometimes this piles up so much that it hampers further treatment. To solve this, infrastructure operators can pump water in the other direction to remove water from filtration. This Filter Backwashing is vital for treatment maintenance.
Image credit: https://www.aquabluepools.net/
Gravity Hills
08/28/25
“Why do objects appear to roll upwards and defy gravity on some hills?”
There are places where nature does not seem to obey the laws of physics. For example, on some hills, objects appear to roll upward instead of downward. There are countless videos on the internet showing the strangeness of these Gravity Hills. But what exactly is happening? Well, it turns out that the slopes of these hills are actually an optical illusion, making downhill look like uphill. These hills usually lack a clear horizon, making it difficult to accurately judge the real direction. Furthermore, a road might be at a slightly different angle than the incline, causing a visual cue mismatch. One example of a gravity hill is in Aragats, Armenia, as seen in the attached picture.
Image credit: https://i.ytimg.com/
Net Positive Suction Head (NPSH)
08/14/25
“What is the minimum pressure needed to avoid cavitation in pumps?”
If pumps don’t have enough pressure, then water vapor can form in the pumps and cause cavitation in the pump blades. Pumps can prevent this from occurring by maintaining pressure above the vapor pressure. The difference between these quantities is known as the Net Positive Suction Head (NPSH). The NPSH required (NPSH-R) is the pressure at the impeller entrance needed to avoid cavitation, equal to the difference between the stagnation pressure and the vapor pressure at the inlet. The Net Positive Suction Head Available (NPSH A) is the pressure available at the pump inlet above the vapor pressure and losses due to system friction. For functional system operation, NPSH A must be greater than NPSH R.
Static Pressure
08/13/25
“What’s the pressure of a fluid’s presence?”
Fluid pressure comes in all kinds of forms. Fluids will exert a pressure from their presence alone called Static Pressure. Air in a balloon is an example of static pressure.
Stagnation Pressure
08/12/25
“What happens when a moving fluid comes to a halt?”
Many fluids move with a certain speed. But if they’re forced to abruptly come to a halt, they’ll convert all of their kinetic energy into pressure. This Stagnation Pressure is vital for understanding how static and dynamic pressure relate to each other and fluid motion.
Exergy
04/27/25
“How can we quantify the potential of energy in a system that can do work?”
Anergy is the amount of energy in a system that can no longer do useful work. It’s complement, Exergy, is the amount of energy in a system that can do useful work. Exert plus anergy makes total work.
Anergy (Energy)
04/25/25
“What is energy that can no longer do useful work?”
When energy is used, sometimes it can no longer do useful work without a renewed energy supply. This energy is termed Anergy. One common form of anergy is waste heat. According to the second law of thermodynamics, the amount of anergy in the universe always increases with physical processes.
Colloids
03/15/25
“Are there substances that are neither suspended nor diluted in another substance?”
When people talk about substances that exist in another substance, it’s common to place them as being either suspended or diluted. However, a mixture exists between them. These substances, termed Colloids, exist between 1 to 1000 nanometers in size (to small to be visible to the naked eye) and do not settle out over time. Examples of colloids include jello, shaving cream, and milk.
Aquifer Porosity
03/05/25
“How can we quantify how much space an aquifer medium has?”
Aquifers exist because there is a void between rocks. The higher the void, the more water can flow through. This is quantified as the Aquifer Porosity, the ration of empty space within an aquifer medium to the entire volume.
Image credit: https://npr.brightspotcdn.com
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