Question

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

Answer 1

length of pole is 7m
and diameter of pole = 20cm = 0.2 m
so, the radius of pole = 0.1m

now, volume of pole = volume of cylinder = πr²h
= 22/7 × 0.1 × 0.1 × 7
= 22 × 0.01
= 0.22 m²

now, weight = volume × density
here given,
density = 225 Kg/m³
volume of pole = 0.22 m³

now, weight = 225 × 0.22
= 49.5 Kg

hence, weight of pole = 49.5 Kg

Answer 2

The pole is a cylinder.
Volume of cylinder = πr²h

Here, r = 20 /2 = 10cm = 0.1 m
h = 7 m

Volume = 22/7 x 0.1 x 0.1 x 7 = 0.22 m³

Now weight = 225 x 0.22 = 49.5 kg