finding-the-radius-of-a-sphere-given-the-volume

Geometry Teachers Never Spend Time Trying to Find Materials for Your Lessons Again!

Join Our Geometry Teacher Community Today!

http://geometrycoach.com/Geometry-Lesson-Plans/?pa=MOOMOOMATH

The video reviews how to find the radius of a sphere given the volume.

The question that is solved is,

Find the radius of a sphere with a volume of 72 meters squared.

The volume formula is 4/3 pi r cubed.

In order to solve for the radius you have to undo the formula.

Transcript

The radius of a sphere with a volume of 72 m^2

This is a backwards problem. There is no easy way to do it other than just to undo it. Let’s see what we have. We have the volume and we know that volume formula is equal to 4/3 pi radius cubed. We know the volume is 72 so I'm just going to plug in 72. Now the only variable we have in this formula is the radius, but we have to get it by itself by undoing all this stuff. To undo a fraction we multiply by its reciprocal so we are going to flip it upside down and multiply both sides by 3/4 and that cancels out the 4/3 so we will multiply 72 by 3/4 so let’s multiply 3 times 72 and divide that by 4 so the left side will simplify to 54 so we have 54 = pi radius cubed. We are getting closer. Now we need to get rid of pi which is 3.14 so we can just divide by that. We will take 54 and divide both sides by pi so 54 divided by pi and I get 17.9 is equal to radius cubed. Now how do you undo a cube? You take a cube root. What we will do is take the cube root of 17.9 I will show you what to do. Go to the Math button and under Math pick the 4th choice which is the cube root. You can choose it or go down to 4. Enter 17.9 and I will type in instead of pulling down my answer. I get 2.58, so our radius is 2.58 in meters. That is how you find the radius of a sphere from the volume. A little bit of undoing and algebra that you will manipulate.

At MooMooMath we provide helpful Math and Geometry videos to help you figure out how to solve Math problems or review old Math concepts you may need to refresh. If you’re a Math student or teacher, we'd love to have you subscribe and join us! We upload a new video every day

* Subscribe

http://bit.ly/1d8EvIu

Let’s connect

MooMooMath

http://www.moomoomath.com/

* Google+

https://plus.google.com/u/0/+MooMooMath

* Pinterest

https://www.pinterest.com/moomoomath/

Twitter

https://twitter.com/MooMooMath

-~-~~-~~~-~~-~-

Please watch: "Study Skills Teacher's Secret Guide to your Best Grades"

https://www.youtube.com/watch?v=f3bsg8gaSbw

-~-~~-~~~-~~-~-

Tagged under: sphere,radius,radius volume,Volume (Dimension),Mathematics (Field Of Study),moomoomath

Clip makes it super easy to turn any public video into a formative assessment activity in your classroom.

Add multiple choice quizzes, questions and browse hundreds of approved, video lesson ideas for Clip

Make YouTube one of your teaching aids - Works perfectly with lesson micro-teaching plans

1. Students enter a simple code

2. You play the video

3. The students comment

4. You review and reflect

* Whiteboard required for teacher-paced activities

With four apps, each designed around existing classroom activities, Spiral gives you the power to do formative assessment with anything you teach.

Quickfire

Carry out a quickfire formative assessment to see what the whole class is thinking

Discuss

Create interactive presentations to spark creativity in class

Team Up

Student teams can create and share collaborative presentations from linked devices

Clip

Turn any public video into a live chat with questions and quizzes

Tried out the canvas response option on @SpiralEducation & it's so awesome! Add text or drawings AND annotate an image! #R10tech

Using @SpiralEducation in class for math review. Student approved! Thumbs up! Thanks.

Absolutely amazing collaboration from year 10 today. 100% engagement and constant smiles from all #lovetsla #spiral

Students show better Interpersonal Writing skills than Speaking via @SpiralEducation Great #data #langchat folks!

Dr Ayla Göl
@iladylayla

A good tool for supporting active #learning.

The Team Up app is unlike anything I have ever seen. You left NOTHING out! So impressed!