Question

PLS HELP ME.

Two solid cylinders with radii 5cm and 10cm and length 7cm and 5cm respectively are melted and recast into a cylindrical disk of thickness 3cm. Calculate its radius.

Answer 1

Explanation:

v.of cylinder= (pi)r²h

pi used = 22/7

first cylinder (A)= 22/7 x 5² x 7

= 550 cm3

second (B) = 22/7 x 10² x 5

=1571.43 cm3

A + B = 2121.43 cm3

new cylinder:

22/7 x r² x 3= 2121.43 cm3

r² = √2121.43/ (22/7 x 3)

r = 15 cm