Question

the volume of a circular iron rod of length 1cm is 3850cm find its diameter

Answer 1

Volume = 3850 cm3
Length i.e. height = 1 m = 100 cm

Volume = πr2h

22/7 x r2 x 100 = 3850
r2 = 3850/100 x 7/22
r2 = 12.25
r = √12.25
r = 3.5

So, the diameter of the rod is 2 x 3.5 i.e. 7 cm.

Answer 2

Given:

Length of circular iron rod=1 m

Volume of circular iron rod=3850 cubic cm

To find:

Diameter of circular iron rod

Solution:

Length of circular iron rod=1 m

We know that 1m=100 cm

Therefore, length of circular iron rod=1 00 cm

Volume of cylinder=$\pi r^2 h$

$\pi=\frac{22}{7}$

r=Radius of cylinder

h=Height of cylinder

Using the formula

Volume of circular iron rod=$\frac{22}{7}\times r^2\times 100$

$3850=\frac{2200}{7}r^2$

$r^2=\frac{3850\times 7}{2200}$

$r^2=12.25$

$r=\sqrt{12.25}$

r=3.5 cm

Diameter of circular iron rod,d=2r=2(3.5)=7 cm

Hence, the  diameter of circular iron rod=7 cm