In manual transmission, it is common practice to park a car in the first gear on uphills or in reverse gear on slopes - in addition to park brakes of course, but let's assume it is not being used in this case. My question is, if the engine is not running, what is preventing the transmission from rotating the otherway? Why doesn't a car on first gear roll backwards?
I also read somewhere that the gear doesn't matter as long as it is the lowest gear available. So is it okay to park a car in reverse gear on a hill? Why the lowest gear? Is any of this dependent on the type of engine - petrol or diesel?
Apologies for asking so many questions at once, I don't have enough reputations to post them as different threads. :)