Question

A hard wood cylinder of radius 2.0 cm and length 75 cm weighs 800 g. Calculate the density of wood in kg/m³.

Answer 1

Solution:

Given :

• Radius(r) = 2.0cm
• Length(l) = 75cm
• Mass(m) = 800g

To find :

• Density of wood

Solution :

$\large\therefore$Volume (V) = πr²l

= $\sf{\dfrac{22}{7}\times (2.0)^2 \times 75 = \dfrac{6600}{7}g/cm^3}$

• Finding the density now,

$\therefore$ Density(D) = $\sf\dfrac{Mass(M)}{Volume(V)}$

= $\sf{\dfrac{800}{\frac{6600}{7}} = \dfrac{800 \times 7}{6600} = \dfrac{28}{33}g/cm^3}$

= $\sf{\dfrac{28}{33} \times 1000kg/m^3 = 848.5 kg/m^3}$

Hence , Density of the wood is 848.5 kg/m³.

Answer 2

Given:

Radius(r) = 2.0cm

Length(l) = 75cm

Mass(m) = 800g

To find :

• Density of wood

Solution :

Density(D) = $\tt\dfrac{Mass(M)}{Volume(V)}$

Mass = 800g

Volume = ?

$\tt{Finding\ Volume\ of\ cylinder = πr²l}$

= $\tt{\dfrac{22}{7}\times (2.0)^2 \times 75 = \dfrac{6600}{7}g/cm^3}$

= Volume = $\tt\dfrac{6600}{7}$

Now, we have Mass and Volume to find Density.

Finding the density now,

= $\tt{\dfrac{800}{\frac{6600}{7}} = \dfrac{800 \times 7}{6600} = \dfrac{28}{33}g/cm^3}$

= $\tt{\dfrac{28}{33} \times 1000kg/m^3 = {\underline 848.5 kg/m^3}}$

Hence , Density of the wood is 848.5 kg/m³.

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More Formulas for finding Volume.

• Volume of cube = Side³
• Volume of cuboid = l×b×h
• Volume of sphere = 4/3πr³