Conversão de unidades

One of the most fundamental things you need to know in any science is how to convert between units.

You were probably told in elementary school that to convert $1000$ centimeters to meters, you need to divide $1000$ by $100$, because a centimeter is smaller than a meter. This method does work, but in the long run, it can become a disorganized way of converting units.

So, we are going to use something called the factor-label method. The idea behind this is we're going to multiply a quantity by a fraction, which, in theory, is equal to 1. This is best learned by example:

To convert $1000$ centimeters by meters, we multiply the quantity ($1000$ centimeters) by a conversion factor equal to 1:

$$(1000 \text{ cm})\left(\frac{1 \text{ m}}{100 \text{ cm}}\right) = 10 \text{ m}$$

In this method, we write the fraction such that we can cancel out some units that we do not need.

Another example:

Convert $235$ kilojoules to calories.

$$(235 \text{ kJ})\left(\frac{1000 \text{ J}}{1 \text{ kJ}}\right)\left(\frac{1 \text{ cal}}{4.18 \text{ J}}\right) = 56220 \text{ calories}$$

I've provided a unit conversion table as a reference.