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# the unit defining a value... such as a car goes 5 km/sec... why is km on top?

im learning physics.... and i dont understand which values belong on the numerator and denominator

such as km/sec.... or Amps/meters

so my question is WHAT makes a certain unit on top and what determins what goes on bottom

### 2 Answers

- PearlsawmeLv 71 decade agoFavorite Answer
Km/sec, Amps/meter, meter / second, meter/ second^2

kg / m^3, N/ m.

In all these units we have a symbol [/].

[/] means per.

Km/sec means kilometer per second.

Amps/meter means ampere per meter and so on.

When there is no number in front of these units we take the number as 1.

If there is a number, say, 12 km / s, then it is 12 km per second.

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If we do want to say that a car moves 240 kilometers in 20 second,

We can write it in short form of 240 kilometer / 20 second

When 240 are divided by 20 we get 12.

Hence 240 kilometer / 20 second can be written is a simple way

Like 12 kilometers / 1 second.

Simply, we write 12 kilometers / second.

Note that,

240 km / 12 second, 480 km/ 24 second, 120 km/ 10 second,

60 km/ 5s, all are one and the same and the simplest way of writing this is 12 km / 1 second and it is even simpler to write as 12 km / second.

- Anonymous1 decade ago
well it depends on what calculation it is, for example, 10 meters in 5 seconds, the velocity of the object is 10m/5s = 10/5 x m/s so it is 2 x m/s meaning

2 meters is covered in a second

just think about how you say it

"two meters PER second"

hope this clears it up a little

quite simple once you get it!