How would you determine the density of an irregularly shaped rock?
The correct answer and explanation is:
Correct Answer:
To determine the density of an irregularly shaped rock, measure its mass using a balance and find its volume using the water displacement method. Then divide the mass by the volume.
Explanation:
Density is defined as the mass of an object divided by its volume. It is a physical property that helps identify a substance and is usually expressed in grams per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³). For regular objects, calculating volume is simple using formulas. However, irregular objects like rocks do not have standard geometric shapes, so a different method is required to determine volume.
The most effective way to measure the volume of an irregularly shaped rock is by using the water displacement method, which is based on Archimedes’ principle. First, fill a graduated cylinder or overflow can with water and note the initial water level. Next, gently submerge the rock completely into the water. Take care to avoid spilling. Measure the new water level and subtract the initial level. The difference in volume represents the volume of the rock in milliliters (mL), which is equal to cubic centimeters (cm³).
Then, use a digital or mechanical balance to measure the mass of the rock in grams (g). Once both the mass and volume are known, calculate the density using the formula:
Density = Mass / Volume
For example, if a rock has a mass of 300 grams and displaces 100 milliliters of water, the density is:
Density = 300 g / 100 cm³ = 3 g/cm³
This method is simple, reliable, and widely used in laboratories and classrooms. It helps determine the type of material and understand how tightly matter is packed within the rock.