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Working with units: FAQ

Frequently asked questions about working with units

Why is it important to be able to convert rates?

Often, we want to compare two rates that are expressed in different units. We need to convert one of the rates to match the other one in order to make a meaningful comparison.
Practice with our Rate conversion exercise.

How do we go about choosing appropriate quantities for modeling?

It depends on the problem we're trying to solve. We'll want to choose quantities that are relevant to the problem and that we're able to measure directly or indirectly. For example, if we're trying to model the speed of a car, we might want to use distance and time as our quantities.

How can we use formulas and units to solve problems?

By using formulas that relate different quantities to each other, we can use known values to solve for unknown values. Units are important because they remind us what the quantities represent and help us to check our work.
Practice with our Formulas and units exercise.

What are some real-world applications of these topics?

There are countless examples! Engineers use rate conversions in order to design systems that operate at different speeds or frequencies. Scientists use formulas and units to solve problems ranging from calculating the densities of substances to measuring the rates of chemical reactions. And of course, people in all sorts of professions use these skills to make everyday calculations, such as converting measurements for a recipe or determining how long it will take to drive somewhere based on the speed limit.

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