Why are there different prepositions?

Question

1. ride a motorcycle
2. ride in a limo
3. ride on a bus

Answer 1

dndlsk's points are correct and good to keep in mind, but it is not like the choice of prepositions is arbitrary and illogical. I'll try to explain below how each of these makes sense.

But about prepositions in general --one major reason they can be so tricky is that there are not that many of them in total, and they are used to express SO many different types of relationship that each one ends up having a variety of uses.

Just look a few of them up in a dictionary and you'll see what I mean. To start with look at the following listings for "in" and "on":

http://www.thefreedictionary.com/on
http://www.thefreedictionary.com/in

As for the specific examples you give, it is true that you have to "simply learn them". BUT there is also some reason each preposition ended up being used.

1) "Ride a motorcycle"
This may be used to emphasize that the person is "operating" vehicle (or similarly with an animal, as in "ride a horse"). At any rate, the expression does not emphasize the POSITION of the rider (in which case you might expect a preposition). Rather it points to the simple fact of riding, and what the vehicle, etc,. is that is being ridden. (Compare "drive a car", "pilot a plane/ship"....)

2) "Ride IN a limo (car, etc)"
Note that this covers situations where the rider is actually INSIDE the vehicle, is somehow enclosed.

3) "Ride ON a bus (train, plane, ship, bike...)".
This covers situations in which (unlike #2) the person is NOT 'inside' the vehicle (as with a bike). Otherwise, the emphasis is on going onto something, mounting, 'boarding' or WALKING onto it, and perhaps standing. This is not usually the with #2 -- you don't typically walk into or stand in a car.

Answer 2

Prepositions are idiomatic. You simply have to learn how each is used. You can't translate the prepositions used in one language into another. Verbs that are transitive (which means they aren't followed by a preposition) in English may be intransitive in another language.
Ride a motorcycle OR ride on a motorcyle
Ride in a limo OR ride inside a limo