Recent content by tech99

Another interesting case is the bottom point of a train wheel, which is travelling backwards.

As a radio engineer, it seems to me to resemble some behaviour which was well known by 1910. If we have two resonant circuits of the same frequency that are coupled together closely, then if we apply an initial impulse, damped oscillation will occur at one of two frequencies at random.

Heeling is caused by the couple created by the sideways force of the sails and the opposing sideways lift of the keel. Heeling is opposed by righting moments caused by the weight of the keel and bouyancy.

May I mention again that the leeway angle is equal to the angle of attack of the keel. It is important that the area of the foil is great enough so that the angle of attack at which it operates is small, such as 5 degrees. At small angles the cross section of the foil is not so important because...

For a column in compression, according to Euler's formula, the buckling strength is not sensitive to the yield strength of the material but does depend on the stiffness (modulus of elasticity).

Maybe first consider the function of a fin (or centreboard on a small craft). The sail is a aerofoil in the wind and a fin is an aerofoil in the water. The wind force on the sail may be resolved into two components: one in the forward direction, causing propulsion, and the other at right...

How are you going to measure potential difference without introducing electrons into the process?

If I place an electric circuit, containing a suitable indicator, in the path of an EM wave I can notice a current being created.

The black stains might be silver halides, in which case sodium thiosulfate will dissolve them. As silver is very toxic, to both people and the environment, be careful not to bring contaminated items into a kitchen.

I would suggest the 2 volts is related to the work function of the material. I should have thought that oscillation in the GHz region would occur, corresponding to the dimensions of the sphere and any associated conductors. An electric spark can have a rise time of picoseconds.

I also observed similar effects with a sonic boom. When Concorde was flying over the Atlantic, I would often hear the boom when walking in the countryside in England. But the interesting observation was that Pheasants, that are ground birds, would suddenly squawk and rise before I heard...

Rolls Royce SMR are producing small, modular reactors, and are contracted to build the first new station at Wylfa, UK, and Temelin, Czech Republic. https://www.rolls-royce-smr.com/

The video focuses on imparting information to students. The primary issue for teaching is not this. It is the development of human interactions so students have the best chance of having a fulfilling and happy life; Clearly, human interactions require a human teacher. Schools are being hit by a...

My experience was that Zoom was hated by the students, the teachers were not getting feedback from them and very little learning took place.

I am concerned about using AI to replace teachers. Children seem to have too much exposure to screen time - we are running into widespread problems with mental health issues, ASD and ADHD. A new trend that I have suddenly noticed is to drastically reduce total screen time for under fives to one...