A bar, the mass of which is 21.6 grams, has dimensions of 4x 2.5x 0.8 cm, determine from what substance it is made.

To find out the type of substance from which the specified bar was made, consider the formula: ρx = m / V = m / (l * b * h).

Problem data: m is the mass of the specified bar (m = 21.6 g, in SI m = 21.6 * 10-3 kg); l is the length of the bar (l = 4 cm, in the SI system l = 0.04 m); b – width (b = 2.5 cm, in SI system b = 0.025 m); h – height (h = 0.8 cm, in SI h = 0.008 m).

Let’s calculate: ρx = m / (l * b * h) = 21.6 * 10-3 / (0.04 * 0.025 * 0.008) = 2700 kg / m3.

Answer: The specified bar should have been made of aluminum.