96%, fun! lol. the electric ones were hard and i got the gear one wrong where you have to match up the tabs!
PLus i have a couple of gripes which me a couple of blokes here agree with: the intake on the four stroke engine....due to vacuum from downstroke of piston, not atmospheric pressure alone... the other was the three bulbs in series with a switch bypassing the middle one, now i know there is the path of least resistance and all that but surely at least some current would travel through the bulb. (albeit very dimly! I'd have passed that way!!
[smug mode on] Bow down before my mechanical might!! [smug mode off] Tallika; The engine question is a `trick`. Yes, the air enters the cylinder, when the piston is on the down stroke, but how? The piston moving down creates an area of low pressure, therefore, when the inlet valve opens, the high(er) atmospheric pressure enters the cylinder to restore equilibrium. Hence, the answer is `...by atmospheric pressure`.
But the atmospheric pressure would not push the air through the port if it wern't for the vacuum on the other side of the valve The flow is caused by a differential pressure. Atmospheric pressure is everywhere. The vacuum is the cause of the differential pressure, and hence the flow.... All things being equal: without the piston action, the process isn't going to work. Looks like i have a lot to learn about pulleys and otto engines
The wording is a bit ambiguous; it should really be `...by differential of pressure`. Say for instance the valve was fully open before the piston began it`s down stroke. The suction of the piston alone wouldn`t be enough to draw the required amount of air in, hence why the valve opens part way through the stroke, to create the low pressure area first. True, the whole process would be impossible without the action of the piston, but the fact remains, that the air flows in due to atmospheric differences, not the actual movement of the piston. (You also need to learn how to spell `auto`! )
410 points - 82% If I were under exam conditions I might of concentrated more and got a couple more right, but it's amazing how much of my A level Physics came back to me while doing it.
A level Physics? That was all GCSE technology stuff for me. No wonder they say exams are getting easier. Which is why I failed at 78% as I've not done it for 10 years ****ing Pulleys
Nope, he did mean otto no typo. As in the great inventor that created the 4 stroke or 'otto' cycle. http://inventors.about.com/library/inventors/blotto.htm
I don't know much about electrics, and I guessed at the more complicated pulley arrangements, but the rest were just very very simple school boy physics. You should be ashamed of yourself for getting those wrong.
