Solve for Unknowns in Scientific Equations

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next:

You're on a roll. Keep up the good work!

Take Quiz
Your next lesson will play in 10 seconds
  • 0:01 Determining a Missing Value
  • 0:44 Simple Algebra
  • 3:51 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Login or Sign up

Lesson Transcript
Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Calculating a missing value in an equation is something you may come across in your scientific analyses. As long as you know the relationship between the variables in the equation, as well as the rest of the measured values, this is a relatively straightforward process for you to master.

Determining a Missing Value

As a scientist, a very useful skill to have is to be able to determine unknown values from known ones. In fact, this happens quite frequently as you work through data collection and analysis. For example, you may wish to know the density of an object, but you only know its mass and its volume. Or, maybe you want to know how fast something is travelling (its speed), but only know the distance that object travelled and the time it took to do so.

What's great is that as long as you know the other values, you can easily calculate the missing one by using simple mathematic relationships. Sometimes you may need to reorganize your formulas to get the known values together. But after you've done this, you're free to calculate away!

Simple Algebra

Let's take a look at some examples of how we go about determining a missing value in an equation, which is any value in the equation that has not been measured or collected by other means. First and foremost, you have to know the formula! You may need to simply memorize some of the more basic ones, while others you can often look up online or in texts.

Next, you need to get all of the known values on the same side of the equation. For example, if you have the equation 2 + x = 5, you would subtract 2 from each side to get the unknown value, the x, by itself. You end up with 5 - 2 = x, and when you solve this you get x = 3. Pretty easy, right?

Let's try something a little more relevant. Let's say you have a chunk of copper and you know its density is 8.96 g/cm^3. You also know that the mass of the copper chunk is 25 g. It's not going to be easy to get the volume of your copper piece because there are no 'clean' straight edges to measure along. You could go find a beaker, fill it with water, dunk in the copper chunk, and then measure the volume of water that's displaced. This will certainly get you the volume of your mineral.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create An Account