Question

11. A rectangular piece of tin of size 30 cm x 18 cm is rolled in two ways, once along its
length (30 cm) and once along its breadth. Find the ratio of volumes of two cylinders
so formed.
12. Water flows through a cylindrical pipe of internal diameter 7 cm at 5 m per sec.​

Answer 1

hope this will help you sorry for bad handwriting

Answer 2

Given,

Size of rectangular tin plate = 30 cm × 18 cm

(i) When rolled along its length (30 cm),

Then, the circumference of the circle so formed = 30 cm

Radius(r1) = C/2π = (30 x 7)/ (2 x 22) = 105/22 cm

And height (h1) = 18 cm

Then, volume = πr12h1 = π x (105/22)2 x (18) cm3

If it is rolled along its breadth (18 cm) then,

Circumference = 18 cm

So, radius (r2) = C/2π = (18 x 7)/ (2 x 22) = 63/22 cm

And height (h2) = 30 cm

Then, volume = πr22h² = π x (63/22)² x (30) cm3

Now, ratio between the two volumes

= π x (105/22)² x (18) : π x (63/22)² x (30)

= (105/22)² x (18) : (63/22)² x (30)

= 5 : 3

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