Recent content by Charles Kottler

...The hands in the clocks in the first line of clocks point to 3 O'clock and have a calculated value of 3 so it seems reasonable to me to assume that the clock on the last line has a value of 2. Then just apply the normal rules of precedence...

Many banks are offering 'offset' accounts these days. As the name suggests these offset your current and/or savings account balances against your mortgage. The interest is calculated on the net balance, so if you owe $250,000 on the house and have $50,000 in savings, your mortgage interest is...

For most people, getting started is the problem. Most people struggle to build even a modest amount of savings - to accumulate 3 to 9 months of salary in an account earning next to no interest would take many years. A more realistic approach is to pick a sum you can afford to spend on a regular...

A simple way to see that the speed of light is finite is to bounce light off a distant mirror and time the delay - for a mirror on the moon the round trip for the light takes about 2.5 seconds: https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment

I have seen a similar derivation before - it is essentially a derivation of Lorentz Ether Theory (LET), and I think the maths is sound. I don't think your conclusion is correct. At the end of the video he is not suggesting that a bat might fly faster than sound - he is saying that if bat A hears...

I think Rovelli was talking about space existing in the classical way. As I understood it he was saying that at the smallest scale distance needs to be treated as a quantum measurement in a similar way to energy, with a 'smallest possible' distance existing. He describes space as like a quantum...

If you are talking about sound in a gas, temperature is the main variable factor affecting the speed. With 'normal' sounds the pressure difference is small enough that temperature changes are negligible. A higher frequency can cause a slight increase in speed...

The speed of sound is governed by the elastic properties and density of a substance. For a simple description see: https://www.nde-ed.org/EducationResources/HighSchool/Sound/speedinmaterials.htm Surface waves (gravity waves) are not quite the same as sound waves but the principle is similar...

The location of the moon in its' orbit makes even more difference - about 45,000km between apogee and perigee...

There have been a few articles recently about 'twisted light' - for example: http://phys.org/news/2016-03-optical-slower.html I am not sure whether the light here is actually following a curved path or if it is an interference pattern. This article implies that it is actually twisted so its...

I am by no means an expert, but I would expect the shadow to shrink as the mass increases. If the mass was a black hole the curvature would be such that multiple images of light sources behind it would reach the wall.

I taught myself Basic on a BBC Micro in about 1984 and still think of 'For...Next' loops in those terms. My work for the last 18 years has been supporting ERP systems (HR, Payroll, Financials, inventory etc.) on an IBM server. The code is generally written in very old languages - RPG dating from...

Geothermal. Go and set up camp by a lava flow or hot spring :smile:. [sorry, didn't read the title... and on second thoughts a fire might be easier anyway.]

In simple terms (the way I think about things...) the air molecules outside the straw move in random directions, applying equal pressure in all directions. The molecules moving inside the straw have a greater speed along the axis than across it (because momentum is lost in colliding with the...