Combination of Solids Solution12





In this page combination of solids solution12 we are going to see solution some practice questions of the worksheet combination of solid worksheet2.

Question 12:

A hollow cylindrical pipe is of length 40 cm. Its internal and external radii are 4 cm and 12 cm respectively. It is melted and cast into a solid cylinder of length 20 cm. Find the radius of the new solid.

Solution:

length of cylindrical pipe (h) = 40 cm

internal radius of the pipe (r) = 4 cm

external radius of the pipe (R) = 12 cm

Height of cylinder = 20 cm

Volume of hollow cylindrical pipe = Volume of cylinder

             Π h (R² - r²) =  Π r² h

             h (R² - r²) =  r² h

             (40) (12² - 4²) =  r² (20)

             (40) (144 - 16) =  r² (20)

             (40) (128)/20 =  r²

             r² = (40) (128)/20

             r² = 2 (128)

          r = √256

          r = √16 x 16

          r = 16 cm

Therefore radius of cylinder = 16 cm

combination of solids solution12  combination of solids solution12