density of block

Question

The sides of a certain rectangular wood block were measured 0.1294 meters, 7.41 centimeters and 9.4 millimeters. The mass of the block was measured to be 55.917 grams on an analytical balance. Determine the density of this wood and record in the correct number of significant digits. 

Answer 1

Density = mass / volume

So, all we need to know is the mass of the object which is given to us as 55.917 grams, and the volume of the object, which we can calculate from the given dimensions, as follows:

Volume = L x W x H but we need to put them all in the same units. I'll choose to use cm.

0.1294 m x 100 cm/m = 12.94 cm

7.41 cm

9.4 mm x 1 cm/10 mm = 0.94 cm

So volume = 12.94 cm x 7.41 cm x 0.94 cm = 90.1 cm³

Density = 55.917 g / 90.1 cm³ = 0.6206 g/cm³ = 0.62 g/cm³ (2 sig. figs.)