Volume Revision

[whitney]

A hollow rubber ball is used for a game of football in a school playground. the exterior radius of the ball is 12cm. The thickness of the rubber is 4mm. Calculate the volume of rubber used in making the ball.

 

[Deleted member 4993]

A hollow rubber ball is used for a game of football in a school playground. the exterior radius of the ball is 12cm. The thickness of the rubber is 4mm. Calculate the volume of rubber used in making the ball.

What is the volume of a sphere with radius = r?

 

[galactus]

Remember to use consistent units. Both radii in mm or cm.

Find the volume of the inner hollow sphere.

Find the volume of the outer sphere.

Subtract the two volumes to find the volume of rubber.

 

[whitney]

Thank you. I was able to figureout the answer of 700cm cubed. Thanks again

 

[Denis]

Thank you. I was able to figureout the answer of 700cm cubed. Thanks again

Good job, Whitney; to be precise: 699.963598....

 

[Deleted member 4993]

Thank you. I was able to figureout the answer of 700cm cubed. Thanks again

Good job, Whitney; to be precise: 699.963598....

How did you get that ???

I get 748.2184615 (using Excel)

4/3 * pi * [(12.4)^3 - 12^3]

or you can approximate by 4*pi*12[sup:1zxj87ai]2[/sup:1zxj87ai]*0.4 = 723.8229474 = 724

 

[galactus]

SK, the OUTSIDE is 12 cm. Thus, the INNER is 12-.4=11.6 because the shell is .4 cm thick

\(\displaystyle \frac{4}{3}{\pi}(12^{3}-(11.6)^{3})=699.963\)

You used the INNER as 12 cm.

 

[Deleted member 4993]

Ahhh ... I missed that exterior part...

Don't have to say Denis.... I am going ... I am going .... right to the corner....

 

[whitney]

Yes it was 699.963, but what I failed to input was the rounding direction at the beginning

 

[Denis]

Don't have to say Denis.... I am going ... I am going .... right to the corner....

45 minutes this time, not 30 minutes :shock: