A wooden pole is 7 m high and 20 cm in diameter. Find its weight if the wood weighs 225 kg per m³.

Given weight = 225 kg/m³

Given height = 7 m and diameter = 20 cm = $\dfrac{20}{100}$ = 0.2 m

Radius = $\dfrac{\text{Diameter}}{2} = \dfrac{0.2}{2}$ = 0.1 m

Volume of cylinder = πr²h.

Putting values in the formula we get,

$\text{Volume of wooden pole } = \dfrac{22}{7} \times (0.1)^2 \times 7 \\[1em] = 22 \times 0.1 \times 0.1 \\[1em] = 0.22 \text{ m}^3.$

Since weight of 1 m³ of wooden pole = 225 kg.

∴ Weight of 0.22 m³ of wooden pole = 225 × 0.22 = 49.5 kg.

Hence, the weight of the wooden pole = 49.5 kg.