# Thread: surface area and volume

1. ## surface area and volume

sorry,if i had done any mistake,because i am new to these forums..

A cylindrical jar of radius 6cm. contains oil.Iron spheres each of radius 1.5c.m. are immersed in the oil.How many spheres are necessary to raise the level of the oil by two centimeters?

cs

2. Originally Posted by rickymylv
sorry,if i had done any mistake,because i am new to these forums..

A cylindrical jar of radius 6cm. contains oil.Iron spheres each of radius 1.5c.m. are immersed in the oil.How many spheres are necessary to raise the level of the oil by two [COLOR=Black]centimeters?
...
The additional volume of the oil is:

$V=\pi\cdot 6^2\cdot 2 = 72\pi\ cm^3$

This is caused by spheres with a volume of:

$V_{sphere} = \dfrac43\cdot \pi \cdot \left(\dfrac32\right)^3 = \dfrac92 \pi\ cm^3$

Now you can calculate the number x of the spheres :

$72\pi\ cm^3 = x \cdot \dfrac92 \pi\ cm^3$

I've got x = 16