Working with pi: simplifying 4/3pir^3

[staceyrho]

when I have 4/3pir^3. What am I doing with the 4/3? Do I multiply it X's pi? It's been a long time since I've worked with pi, I need someones help.

thanks,
Stacey

 

[galactus]

That's the volume of a sphere formula.

Yes, you multiply it by pi. Along with r^3.

\(\displaystyle \L\\\frac{4}{3}{\pi}r^{3}\)

 

[staceyrho]

So when I multiply 4/3pi that = 4.186666667?
then I multiply that by my radius?

 

[Denis]

So when I multiply 4/3pi that = 4.186666667?
then I multiply that by my radius?

You multiply by radius to the power 3 : that's what r^3 means

The formula can be looked at this way: (4 * pi * r * r * r) / 3

 

[staceyrho]

thanks for the help. So now i'm trying to find the solution for two questions that are part 1 and part 2.

question(The radius of the plante Saturn is 5.85X10^7m, and it's mass is 5068X10^26kg. Find the density of Saturn (It's mass divided by its volume) if the volume of a sphere is 4/3pir^3. Answer in unit of g/cm^3)

question 2 (fint eht surface area of Saturn if the surface area of a sphere is given by 4pir^2. answer in units of ft^2.

for question 1 i'm then taking my 4XpiXr^3 which I get 12.56Xr^3. Then here's where i'm also confused my radius is 5.85X10^7m. What do I do what that 10^7?

This is the answer I got and correct me if i'm wrong

4xpixr^3= 220.428x10^7.