## Unit Conversions

One of the most critical elements of problem solving in engineering, besides identifying the problem and exploring solutions, is to be able to accurately calculate quantities in the proper units of measure.

Converting inches to feet, miles to meters, gallons to liters, hours to seconds, nickels to dollars are some of the many types of conversion problems that we often face.

In order to properly set up a unit conversion equation there are three basics types of information or variables that we need to identify.

They are:

Knowns (Given or Have), Unknowns (Want or Need to find), and Conversion Factors (Constants that relate one variable to another)).

Once that information has been identified and segregated, we need to set up the equation.

Unknown = (Known) x (Conversion Factor)

It is important to set up the equation where the final answer is expressed in the desired units, and where the undesired units are cancelled out.

Conversion factors are found in tables, charts and in several sites on the internet.

The following step-by-step procedure can be used to solve any unit conversion problem:

Steps for unit conversions

1. Write out the units you have (when appropriate as a fraction):
2. Write out the units you want to end with:
3. Determine appropriate conversion factors (in some cases, there will be more than one conversion factor for each of the units you have):
4. Evaluate appropriate arrangement for fractions (that is, what units belong in numerator (top) of fraction? What units need to be in denominator (bottom)?
Remember, units cancel when one unit is in numerator and the other is in the denominator). Remember that when you multiply fractions (as you will in step below), you can cancel units ONLY when they appear in both the numerator and
the denominator.
5. Set up the conversion by writing the fractions in a row with multiplication signs in between
6. Evaluate. Do the original units cancel so that you are left with ONLY the units asked for? If not, repeat steps 3 and 4 until you are left with appropriate units:
7. Multiply across top and bottom:
8. If necessary, reduce the fraction.

Example: Convert 15 inches into feet.

Known: 15 inches, Unknown: X feet, and Conversion Factor: 12 inches = 1 ft, or       (1 foot / 12 inches).

Equation:  (15 inches) x (1 foot / 12 inches) = X feet

By cancelling out inches, and dividing 15 by 12, we get: 1.25 feet as our final answer.

As you can see, it is easy to convert units, as long as you follow the simple process outlined earlier. Please note that units can fall in several categories as depicted by the graphic above. Angles, Area, Energy, Length, Speed, Power, Volume, Times, Rate, Temperature, are some of the many quantities and measurements that can be calculated.

In case you did not follow that approach, and still have questions on how to convert units; below you will find a few YouTube videos that will attempt to explain the same concept with different variations to the approach.

Check them out and find the one that makes the most sense to you.

Here is another link that you may want to visit:

What do you think? Did you find a lesson that fits your learning style? Did you get the idea and the concept of Unit Conversion? We hope so.

Now that you have learned the basic principles of unit conversion, is time to practice and see how good you really are.

The following conversion factors will come handy whenever you need to find out the relationships between various constants.

The website below gives you a few problems to test your newly acquired skills. Copy and paste to your browser.

http://www.sciencegeek.net/Chemistry/taters/Unit0Metrics.htm

You can also test your knowledge by using the Quizlet website below to try out a few practice problems. You can also use the flashcard option to review.

https://quizlet.com/19247322/metric-conversion-practice-flash-cards/

You are now an expert, and it is time to take a final assessment and see if there is anything more that you need to practice, before you can move on to the next STEM topic.

Copy and paste the following Quizlet link to your browser and see how good you really are. If not that good yet, keep practicing and taking the assessment until you reach a 90% rate or better. Good Luck!!!!!

https://quizlet.com/_3cikwl

Hope you were able not only to learn and practice the concept of Unit Conversion, but we also hope that you found the lesson to be effective (fitting to your learning style) and most of all, FUN.

Great Job!

## Welcome to STEM Prep 101!

Welcome to STEM Prep 101! To navigate your way to success, we are providing short training courses by subject matter. You will find math facts, unit conversions, and some information on cellular biology. Want to see more? Leave us a comment or suggestion!

# Discover some special characteristics about 45°-45°-90° triangles!

A 45° – 45° – 90° triangle is an isosceles triangle… the two legs are the same length. The hypotenuse is always the length of the leg times the square root of two! So one quick and easy trick to help you remember is that there are two angles that are the same, so two sides are the same, and the third side will ALWAYS be the length of the leg multiplied by the square root of two!

The KEY is that you EXPECT to see the square root of two on the hypotenuse… so what happens if the hypotenuse is a whole number? Let’s say the hypotenuse is 14… what will the length of the legs be?

Remember, you EXPECTED to see the square root of two on the hypotenuse, but it isn’t there, so all you do is divide the hypotenuse by two, then multiply that figure by the square root of two and that is the length of the legs! (Remember, the two legs are the same length!) So in this case, each leg will be 7 times the square root of two!

Let’s give it a try… You have a 45°-45°-90° triangle and one of the legs is 6. What are the length of the other leg and the hypotenuse?

Did you get 6 for the other leg, and 6 times the square root of two for the hypotenuse?

Let’s try another one! You have a 45°-45°-90° triangle and the hypotenuse is 24. What are the lengths of the legs? (Hint: remember what you EXPECT to see!)

Did you get 12 times the square root of two for each leg?

What would the length of the legs be if the hypotenuse is 15?

All you have to do, is remember what you expect to see! If you got 7.5 times the square root of two, you are right on the money!!

Remember the KEY is what you EXPECT to see!! Click on the video below to see another explanation of this relationship.

# Another special right triangle is the 30°-60°-90°.

The 30°-60°-90° has a very special relationship between it’s sides. First, you can tell that all three sides will be different lengths because the three angles are different. Similar to what we learned in the 45°-45°-90° triangle, the KEY is what you EXPECT to see!

With the 30°-60°-90° triangle, the first thing you do is locate the 30° angle. No matter where it is, the side opposite (or across) from the angle will be the shortest side of the triangle. That side is the KEY! From there, you can calculate the length of the other two sides of the triangle quickly and easily because the hypotenuse (the side opposite of the right (90°) angle will ALWAYS be twice as big as the short side!

The last side, the side opposite o the 60° angle is ALWAYS the short side times the square root of three! So there is a simple trick to help you remember which special triangle uses which square root… the 30°-60°-90° has three different angles so it has the square root of three, where the 45°-45°-90° triangle has two different angles so it uses the square root of two!

Let’s try a few problems! You have a 30°-60°-90° triangle and the side opposite the 30° angle is 6, what are the lengths of the other two sides?

If you said the side opposite the 90° angle is 12 and the side opposite the 60° angle is 6 times the square root of three you got it!!

What if the hypotenuse is 30? What would the other two sides be?

The short side (side opposite the 30° angle) is 15, and the side opposite the 60° angle is 15 times the square root of three!

Let’s see if you can figure this one out. (Hint: use the same skill set you learned with the 45°-45°-90° triangle and what you EXPECT to see!) You have a 30°-60°-90° triangle and the side opposite the 60° angle is 15. What are the lengths of the other two sides?

Did you get it? First, what did you expect to see on the side opposite the 60° angle? The square root of three right? But it isn’t there, so, in this case, you divide whatever value is there by three… in this case you get 5. So the short side (side opposite the 30° angle) will be 5 times the square root of three! The hypotenuse is twice as big, so it will be 10 times the square root of three!

If you practice these exercises until you remember what you EXPECT to SEE, you will have no problems being able to solve these special right triangles! Click below to hear a fun rap to help you remember the relationship of the 30°-60°-90° triangle.

# Other Special Right Triangles

There are some other quick ways to solve for the lengths of the sides of special right triangles… these are your most common right triangles also known as:

• ## 8 – 15 – 17

The great thing about knowing these triangles, is that any multiple will also be a right triangle! Let’s take a look…

So a triangle with sides that are 3″, 4″, and 5″ will ALWAYS be a right triangle. It could be 3 cm, 4 cm, 5 cm; 3′, 4′, 5′; 3 mi, 4 mi, 5 mi… in each case, they will each be a right triangle! The KEY is what you EXPECT to SEE! The longest side, is ALWAYS the hypotenuse. So, if I tell you the hypotenuse is 5 mm, and one of the other sides of the triangle is 4 mm and ask you, what is the length of the third side? 3 mm is right on the money! Remember, it works with any multiple as well! 3-4-5, 6-8-10,9-12-15, 12-16-20, 15-20-25, and so on and so on! If you know these four special right triangles, you will be able to solve a number of problems quickly and easily!

## Click below to see more fun right triangle videos!

This next video is AMAZING!!! Another great resource to have up your sleeve!

# Let’s check for understanding!

## Awesome Math Facts

Fun Review Video

As you learned in your 8th grade math class and reviewed in your 9th grade Integrated I course, solving systems of linear equations by linear combination.

Both equations were written in Standard form. The addition or fused combination of both equations cancelled out the “x” value, giving us an opportunity to solve for the “y” value. Once this is achieved, Substitute the “y” into the any of the two equations, then solve for “x.” The solution is going to be an ordered pair. (4,-3).
Solving Systems of Equations by Substitution and Graphing
We can substitute y in the second equation with the first equation since y = y. The solution of the linear system is (1, 6). You can use the substitution method even if both equations of the linear system are in standard form. Just begin by solving one of the equations for one of its variables.
The systems of equations can have an array of solutions, for example if lines are parallel, then the system has no solutions.
As the example above indicates, if the system of equations intersect exactly at one point, then the solution is only one ordered pair.
If the linear equations Coincide (meaning the same line) then the system has an infinite number of solution.
Solve the Systems of Equations by Graphing

## Cellular Biology for sixth graders

What do you, a bacteria, an earthworm, and a potted plant have in common?

You are all made of cells, from one single cell to millions and millions of cells that all work together to keep you moving and shaking.

Cells are the building blocks of life, they come in two basic types, plant cells, and animal cells.

Cells are tiny, so small they have to be seen through a microscope, but as you can see there are even smaller structures within each cell called organelles that each have a specific function that helps the cell to live, grow and reproduce.

• nucleus
• lysosome
• mitochondria
• chloroplast
• cell membrane
• ribosome
• vacuole
• endoplasmic reticulum
• mitochondria

Sometimes it is helpful to think of the cell as an organization with the different parts doing different jobs but working together for a single purpose.  How about a city?  Can you match the following organelles with the corresponding part of the city?

1. The nucleus is the control center of the cell, it directs all the cell’s activities including reproduction.
2. The cytoplasm is a gel-like substance in which all the organelles float within the cell membrane.
3. The cell membrane is the outer boundary of the cell, it separates the cell from its environment and controls what enters and exits the cell.
4. The mitochondria are the powerhouses of the cell, they convert glucose and oxygen into energy for the cell to use for all its functions.
5. The lysosomes are organelles that break down worn out cell parts and disposes of them.
6. The ribosomes are tiny organelles that link amino acids together to form proteins, that are then used to build and repair tissue.
7. The chloroplasts are green organelles found only in plant cells that capture energy from the sun and convert it into food for the cell.
8. The endoplasmic reticulum is a series of tunnel-like structures that serve to transport materials from one part of the cell to another.
9. The vacuoles are storage sites within the cell that store food and water for the cell.  Plant cells have one large vacuole, while animal cells have several small ones.

Copy the link below and paste it into your browser and click on the Flash Cards button to review terms; when finished close the window.

https://quizlet.com/_3dbcrv

Not all cells look alike, they have a structure that matches its function.  In other words, the shape it has helps it do the job that it has to do.  Check out the chart below to see a few examples of how the shape of a cell helps it do its job.

Cells divide and reproduce through a process called mitosis. At the culmination of this process two daughter cells are produced that are identical to the original cell.  It is through this process that organisms are able to grow and repair tissues after an injury.

Take a look at the events that take place during each of the different phases of the cycle.

As you can see the cell spends most of its time in  in interphase where it grows and replicates its DNA and prepares to divide.

This brief video describes the various events of each of the phases of cell division.

Quiz

1. Which organelle is responsible for disposing of waste products within the cell?
2. Mitochondria chloroplast              C. ribosome                 D. lysosome

1. Which part of the cell regulates what enters and exits the cell?
• Cell membrane endoplasmic reticulum      C. vacuole        D. nucleus

1. Which organelle is responsible for protein synthesis?
2. Mitochondria ribosome    C. chloroplast              D. cell wall

1. True or False, Animal cells have one large vacuole, while plant cells have several small vacuole.

1. True or False, The nucleus is responsible for cell division.

1. True or False, Mitosis is the process by which sex cells are formed.

1. During which phase of cell division does DNA replication take place?___________________.

1. Why is it important that DNA is replicated before cell division takes place?___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. What would happen to our body’s ability to repair itself after an injury if cell division did not take place?___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. How does understanding cell division help us to understand cancer?__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

## What would you like to see?

Leave us a comment about things you would like to see featured in any or all of the categories and we will get them addressed as soon as possible! Have fun and be blessed!