13/05/2019
The question in the accompanying attachment was presented to final year students in their exams. It was worth 20% but was a do or die question. The student who was sure of his principles scored a quick bonus.
Obviously, this question was a one time event and could not or never was repeated. It would be a free 20% ever after.
The fact is energy cannot be created no destroyed. Power is the rate of providing energy rather than a lump sum which a Joule is (or calorie)
So if you have a super dooper 300 kw car and want to experience 300 kw, you have to find somewhere to dump the 300 kw, basically to the atmosphere in the form of drag, rolling resistance etc.
But at 300 kw don't pretend you will get 10 kms per litre as the sticker in the window says. Kw's requires fuel so 3 kms per litre would be the norm.
Nowadays, car manufacturers give out very few details about engines except maximum power, maximum torque and the 0 to 100 kms /hr time.
What is of interest is the unrestricted maximum speed so that the resistance to motion and hence real life fuel consumption can be worked out.
There was also a figure which used to be given out called BMEP (brake mean effective pressure ) which gave a good idea of the state of tune of a car. Turbo cars have a high BMEP so can be considered highly tuned.
Finally, instead of the 0 to 100 time, the standing quarter mile gave a better indication of true acceleration in relation to distance and a better idea what the torque curve looked like. Peak torque is meaningless really.
