Recent content by saddlestone-man

Many thanks for the replies so far. If I may ask a supplementary question: would the red shift I see in my reflection in the mirror be the same seen by an observer standing on the mirror? Or would the fact that the light I see has travelled a round-trip distance twice that of the light...

If I park my space ship close to a highly-reflective mirror in space and then accelerate away from it at exactly 90 degress to its surface, how will the image I see of myself change as I approach the speed of light? best regards ... Stef

I think what I'm saying is .... say you had two long sequences of numbers, one of which was extracted from the value of Pi and the other which was the tail end of a large long division (whose answer did not have an infinite number of digits): would you be able to tell the difference?

Many thanks for the answers. I wondered that there may be some sequences of digits (say 1,000 repetitions of the same digit, or something like 123123123123123123 ....) which would indicate that the value had converged, which of course in the case of Pi is impossible.

As the value of Pi is taken to more decimal places, does any sequence of digits become equally likely? I'm thinking of sequences like ...123456789.... ...333333... and so on. best regards ... Stef

Hello All I have a reference in a 1930s journal to potassium bichromate. Is this the same as potassium dichromate K2Cr2O7 ? ie dichromate is the modern terminaology to use. Searching on the www almost always finds the dichromate when I search for the bichromate, but maybe this is just the...

Very witty. It avoids the question of whether the scales are measuring mass or weight.

Ah OK, that's interesting, and confusing. The scales I'm using are for weighing items to go into the post. They are giving a reading in kgm. But surely if I used the scales on the Moon, then they would give a reading of 1/6 what it was on Earth, whereas the mass of the object would stay the same.

This is Meccano, made in the UK. I think Erector is the US version? Yes I would agree that the gear box is probably very lossy. Having just adjusted my test results by a factor or 9.8 (I originally used the weight, rather than the mass) of the weight being lifted, I now get efficiencies ranging...

Did you use the mass of the object in the mgh formula for calculating the work done? I mistakenly used the weight of the object and so was out by a factor of 9.8 for the work done. This makes the efficiency of the motors I tested even worse, by a factor of 9.8. Here's a picture of my set-up...

Many thanks. So to be clear, I would have to weight the object and then divide this by 9.8 to get the mass?

Hello The formula Mgh is commonly accepted as the work done by raising a mass by a distance h, where M is defined as the mass of the object raised. However, is this really the mass, or the weight, simply obtained by weighing the object? If it's the weight, then doesn't the equation...

Many thanks, I'll add some photos tomorrow. Yes the voltage is correct. Interesting about the efficiency of the Lego motors. Sound like my calculation could be correct. The motor I'm testing is an old Meccano one and I'm guessing it was made more for low cost than efficiency. Also it doesn't...

Hello All I've conducted an experiment to work out the efficiency of a small motor, and it comes out to be very low. Have I done my calculations correctly? I connected the motor to a gearbox (made from Meccano) and a winch and used it to lift a weight. I measured the DC voltage across the...

I completely agree ... just start writing, it doesn't have to be the beginning you start with. It's best to start with whatever you are most confident/comfortable with, and then work outwards. The great thing about writing today on a word processor package it that copying/cutting/pasting is so...