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## Units and Measurement

Question : 1

Total: 33

**Solution:**

(a) The volume of a cube of side 1 cm is given by, V = ( 1 c m ) 3

or V = ( 10 − 2 m ) 3 = 10 − 6 m 3 .

(b) The surface area of a solid cylinder of radius r and height h is givenby :

A = Area of two caps + curved surface area

= 2 π r 2 + 2 π r h = 2 π r ( r + h )

herer = 2 c m = 20 m m ,

h = 10 c m = 100 m m

∴ A = 2 ×

× 20 ( 20 + 100 ) m m 2

= 15086 m m 2

= 1.5086 × 10 4 m m 2

= 1.5 × 10 4 m m 2

(c) Herev = 18 k m h − 1

=

= 5 m s − 1

t = 1 s , x = v t = 5 × 1 = 5 m

(d) Relative density of lead = 11.3, density of water = 1 g cm– 3

We know that relative density of lead=

∴ density of lead = relative density of lead × density of water

= 11.3 × 1 g c m − 3

= 11.3 g c m − 3

Also in S.I. system density of water = 103 kg m– 3

∴ density of lead = 11.3 × 10 3 k g m − 3

= 1.13 × 10 4 k g m − 3

or

(b) The surface area of a solid cylinder of radius r and height h is givenby :

here

(c) Here

(d) Relative density of lead = 11.3, density of water = 1 g cm

We know that relative density of lead

Also in S.I. system density of water = 10

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