Question -
Answer -
Volume of the solidsphere = (4/3)πr3
Volume of twenty sevensolid sphere = 27×(4/3)πr3 = 36 π r3
(i) New solid ironsphere radius = r’
Volume of this newsphere = (4/3)π(r’)3
(4/3)π(r’)3 =36 π r3
(r’)3 =27r3
r’= 3r
Radius of new spherewill be 3r (thrice the radius of original sphere)
(ii) Surface area ofiron sphere of radius r, S =4πr2
Surface area of ironsphere of radius r’= 4π (r’)2
Now
S/S’ = (4πr2)/(4π (r’)2)
S/S’ = r2/(3r’)2 =1/9
The ratio of S and S’ is 1:9.