Question

please solve this problem​

Answer 1

$\huge{\orange{\underline{\red{\mathbf{SOLUTION}}}}}$

Volume of the iron pillar = Volume of the cylinder + volume of the cone

$\orange{cylinder\::-}$

Radius = diameter / 2

= 20/2 = 10cm

Height = 2.8 m

= 280 cm

Volume = $\pi$$r^2h$

= 22/7 × 10 × 10 × 280

= 88000$cm^3$

$\red{Cone:-}$

Radius = diameter/2 = 20/2 = 10cm

height = 42cm

volume = 1/3 $\pi$$r^2h$

= 1/3 × 22/7 × 10 × 10 × 42

=4400 $cm^3$

⛬ Total volume = 88000 + 4400

= 92400$cm^3$

⛬ Total weight of the pillar at a weight of 7.5 g per 1 $cm^3$

=92400×7.5

=92400×7.5=693000 gms

=92400×7.5=693000 gms=693000/1000 kg = 693 kg.

Answer 2

Given that:-

Height of Iron pillar = 2.8m = 280cm

Radius of Iron pillar = D/2 = 20/2 = 10cm

height of cone = 42cm

Volume of whole pillar = volume of cylinder + volume of cone

                                      = πr²h + $\frac{1}{3}$πr²h

                                      = πr²(h + $\frac{1}{3}$h)

                                      = $\frac{22}{7} * 10^{2} *$$(280 + \frac{1}{3} * 42)$

                                      = $\frac{2200}{7}$$(280 + 14)$

                                      = $\frac{2200}{7}$ $* 294$

                                      = 2200 * 42 = 92400 cm³

Density of pillar = 7.5g/cm³

Weight of 92400cm³ pillar = 7.5 * 92400 = 693000 g = 693Kg

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