A block of wood 3.0cm on each side has a mass of 27g. What is the density of this block? Answer: 1.0 #"g/cm"^3#.

1 Answer
Jun 9, 2015

Answer:

The 3.0 × 3.0 × 3.0 comes from the formula for the volume of a rectangular solid.

Explanation:

You can read about how to calculate density here.

The formula is

#"Density" = "Mass"/"Volume"#

You have to know the mass and the volume to calculate the density.

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You know that the mass is 27 g.

Now you have to calculate the volume.

You know that your sample is a block that is 3.0 cm on each side.

The formula for the volume of a rectangular solid is

#V = l×w×h#

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In this case, #l = w = h = "3 cm"#. So

#V = lwh = "3.0 cm × 3.0 cm × 3.0 cm" = "27 cm"^3#

#"Density" = "Mass"/"Volume" = "27 g"/("27 cm"^3) = "1.0 g/cm"^3#

In each of your calculations, the number of decimals is controlled by the number of significant figures.

Every number you use in your calculations has 2 significant figures, so you can have only 2 significant figures in your answers.