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RS Aggarwal Solutions Class 9 Mathematics Solutions for Volume And Surface Area Of Solids Exercise 15B in Chapter 15 - Volume And Surface Area Of Solids

Question 23 Volume And Surface Area Of Solids Exercise 15B

1cm3 of gold is drawn into a wire 0.1mm in diameter. Find the length of the wire.

Answer:

ANSWER:

We know that

1cm3 = 1cm × 1cm × 1cm

1cm = 0.01m

So the volume of gold = 0.01m × 0.01m × 0.01m

We get

Volume of gold = 0.000001m3 ….. (1)

It is given that

Diameter of the wire drawn = 0.1mm

So the radius = 0.1/2 = 0.05mm = 0.00005 m ……. (2)

Consider length of the wire = h m ……. (3)

We know that

Volume of wire drawn = Volume of gold

By substituting the values using (1), (2) and (3)

πr2h = 0.000001

On further calculation

Π × 0.00005 × 0.00005 × h = 0.000001

So we get

h = (0.000001 × 7)/ (0.00005 × 0.00005 × 22) = 127.27m

Therefore, the length of the wire is 127.27m.

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