Density Flashcards

All 6 cards in this deck

What is the equation linking density, mass and volume?

$\text{density} = \dfrac{\text{mass}}{\text{volume}}$ or $\rho = \dfrac{m}{V}$

In the density equation, what are the SI units of density, mass and volume?

Density in $\mathrm{kg/m^3}$, mass in $\mathrm{kg}$, volume in $\mathrm{m^3}$.

What are the steps to calculate the density of an object?

e.g. mass $= 30$ g, volume $= 10$ cm$^3$

1. Check the units match: g with cm$^3$ gives g/cm$^3$.
2. Divide mass by volume: $30 \div 10$.
3. Density $= 3$ g/cm$^3$.

What are the steps to find the volume of an object from its density and mass?

e.g. density $= 2$ g/cm$^3$, mass $= 10$ g

1. Write the equation: $\rho = \dfrac{m}{V}$, so $2 = \dfrac{10}{V}$.
2. Rearrange: $V = \dfrac{m}{\rho} = \dfrac{10}{2}$.
3. Volume $= 5$ cm$^3$.

What are the steps to convert a density in g/cm$^3$ into kg/m$^3$?

e.g. $2.5$ g/cm$^3$

1. Multiply the number by $1000$: $2.5 \times 1000 = 2500$.
2. Write the new unit: $2500$ kg/m$^3$.

True or false? If a block of aluminium is cut in half, each half has half the density of the whole block.

False. Density is unchanged — both the mass and the volume are halved.