OldTony

It seems to me that if you lift the reservoir container as well as the air driven pump that would work better as it wouldn't have to suck so hard.

Apart from the other comments it seems to me that to let air out you need to let water in requiring two apertures both below the outside waterline. The inlet at the bottom of the vessel and the outlet near the top. This would seem to need enough ballast to sink it while full of air. If you wan't horizontal movement as the object sinks it seems to me that in the end you are employing gravity. Although it doesn't answer the OP's question stubby wings working on the same principle as glider wings in air would do the trick.

Ah well, I fell for that one - or perhaps a touch of "Two nations divided by a common language ".

Certain caterpillars, moths and butterflies have evolved to have imitation eyes so perhaps having such does confer a reproductive advantage ?

This is just an observation but seems relevant to the discussion. It is very difficult, apparently, for the human mind to produce a long list of truly random numbers. There are recognised tests for randomness and rather strangely, I think, that even if you produced a list of numbers by a method such as rolling a dice it may well produce a list of numbers that would fail a test for randomness. For that reason you can purchase a book of random numbers that agree with the rules of randomness.

Thank you, you are very kind. We are both chugging along with the help of modern science - bypass and pacemaker for me and a heart valve and pacemaker for my wife

Lol - I just looked up where you live - we didn't go to the same school but I spent a total of 11 years out my total of 22 years service at RAF Locking, near Weston-Super-Mare as an instructor and also a trade standards examiner. In the latter role I spent 4 years working on all aspects of multiple choice tests. More importantly I met and married a Somerset lass and we recently celebrated our 67th anniversary.

It appears to me that this is not really a question about multiple choice questions. As has been pointed out we do not know the parameters given to the question writer such as how many answers should be correct (including none). For some reason it brings to my mind an old conundrum where you are given a card and written on both sides of it are the words "The statement on the other side of this card is not true"

It seems to me it depends on the question One obviously expects there to be only one answer and so the question setter has a duty to make it so. But, for example, how would an examiner mark the following question? What is the square root of 36? a) -6 b)-3 c) +3 d) +6

hi Folks, you really do make me aware of my age One of the first motorbikes I had was a Panther 350 with an ignition timer control on the handle bars. It could give you a nasty kickback if you set it too far advanced when kick starting. On the other hand you could Get a gentle response that I'd describe as soft and soggy when travelling on icy roads. One of the first 4 wheeled vehicles I had was a Ford Thames van with a starting handle. The advice was don't wrap your thumb around the handle so that if it kicked back on starting it could jump out of your hand without hurting too much. BTW That was the early 1960's when I met a girl who happily rode pillion, seemed to get less keen when we got engaged and exerted all her influence on me to acquire 4 wheels once we were married. :)

That's true. I was just pondering what exactly is meant when the word "or" is used. It seems to me that if someone says to two people "I want you or you to do something" he is most likely wanting the exclusive or function to apply. He doesn't need to say "I want you or you to do something but not both of you". Perhaps I was being a bit pedantic, but thought it worth mentioning.

It's worth mentioning that small beer saved many lives in the 19th century . "During the 1854 cholera outbreak in Soho, London, small beer (a low-alcohol beer) played a critical role in saving lives, as brewery workers and residents who consumed it were spared from the contaminated water that caused the epidemic . PubMed Central (PMC) (.gov) +1"

It seems to me that Professor Shercliff is really focussing on transient conditions on switching on or off dc circuits and the operation of ac circuits. I notice the diagram does not include one or more switches therefore I would assume steady state conditions would be the purpose of the question. In any case even during the transient period, as I understand it, Kirchoff's laws apply at any specific point at any specific instant of time. Whether wanted or not every circuit has some inductance and some capacitance which have their effect during the transient period of microseconds or nanoseconds, but once the transient period is over neither has an effect in the steady state.

Just to add. My understanding is that Kirchoff's laws and equations apply to ac circuits if you add " at any given instant of time".

The circuit given is a dc circuit and a radio aerial only transmits when given an ac signal to create a magnetic field. Surely in a dc circuit Kirchoff's equations hold good ?