Question

Plz answer it's very urgent
From chp Surface Areas & Volume ( Class 9)
1) The cube has numerically equal volume & surface area. Find the volume of such a cube.
2)The Curved surface of a cylinder is 1000 cm2 & its diameter is 20 cm. Find the height & the volume of the cylinder.

Answer 1

ANSWER
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ANS 1)

SURFACE AREA OF CUBE = 6 × side^2
VOLUME OF CUBE = side ^3

Let side be a

ACCORDING TO QUESTION,

6a^2 = a^3

=> 6 × a × a = a × a × a
=> 6 = (a × a × a) / (a × a)

=> a = 6

If side = 6 then Volume
= 6 ^3
=> 6 × 6 × 6

= 216 unit cube { ANSWER }

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Ans 2).

CURVED SURFACE AREA OF CYLINDER =
2 π r h

CSA = 1000 (GIVEN)
R = 10 cm ( D/2 )

1000 = 2 × 3.14 × 10 × h
1000 = 6.28 × 10 × h

=> 1000 = 62.8 × h

=> h = 1000 / 62.8

=> h = 15.92 cm

Height = 15.92 cm

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Volume of Cylinder = π r^2 h

Volume = π × 10^2 × 15.92

Volume = 3.14 × 100 × 15.92

Volume = 314 × 15.92

Volume = 1858.88 cm^3 {ANSWER}

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HOPE IT HELPS :):):):):):):)