Cambridge IGCSE Physics (0625) - Conversion of Units

Practice vocabulary flashcards covering SI prefixes, power rules for area and volume, basic and compound unit conversions, and worked problems for Cambridge IGCSE Physics 0625 Making Measurements assessment.

Giga (G)

An SI prefix representing a factor of $10^9$ ($\times 10^9$).

Mega (M)

An SI prefix representing a factor of $10^6$ ($\times 10^6$).

Kilo (k)

An SI prefix representing a factor of $10^3$ ($\times 10^3$).

Deci (d)

An SI prefix representing a factor of $10^{-1}$ ($\times 10^{-1}$).

Centi (c)

An SI prefix representing a factor of $10^{-2}$ ($\times 10^{-2}$).

Milli (m)

An SI prefix representing a factor of $10^{-3}$ ($\times 10^{-3}$).

Micro (µ)

An SI prefix representing a factor of $10^{-6}$ ($\times 10^{-6}$).

Nano (n)

An SI prefix representing a factor of $10^{-9}$ ($\times 10^{-9}$).

Area Unit Conversion Rule

When converting area units raised to a power (such as $\text{cm}^2$ and $\text{m}^2$), square the linear conversion factor; since $1\text{ m} = 100\text{ cm}$, $1\text{ m}^2 = 100^2 = 10\,000\text{ cm}^2$.

Volume Unit Conversion Rule

When converting volume units raised to a power (such as $\text{cm}^3$ and $\text{m}^3$), cube the linear conversion factor; since $1\text{ m} = 100\text{ cm}$, $1\text{ m}^3 = 100^3 = 1\,000\,000\text{ cm}^3$.

Conversion of $250\text{ cm}$ to metres (m)

$$250\text{ cm} = 250 \div 100 = 2.5\text{ m}$$

Conversion of $3.2\text{ km}$ to metres (m)

$$3.2\text{ km} = 3.2 \times 1000 = 3200\text{ m}$$

Conversion of $0.045\text{ kg}$ to grams (g)

$$0.045\text{ kg} = 0.045 \times 1000 = 45\text{ g}$$

Conversion of $750\text{ g}$ to kilograms (kg)

$$750\text{ g} = 750 \div 1000 = 0.75\text{ kg}$$

Conversion of $850\text{ mm}$ to metres (m)

$$850\text{ mm} = 850 \div 1000 = 0.85\text{ m}$$

Conversion of $2.5\text{ hours}$ to seconds (s)

$$2.5\text{ h} = 2.5 \times 60 \times 60 = 9000\text{ s}$$

Conversion of $45\text{ minutes}$ to seconds (s)

$$45\text{ min} = 45 \times 60 = 2700\text{ s}$$

Conversion of $3\text{ days}$ to seconds (s)

$$3\text{ days} = 3 \times 24 \times 60 \times 60 = 259\,200\text{ s}$$

Conversion of $5.6\text{ }\mu\text{A}$ to amperes (A)

$$5.6\text{ }\mu\text{A} = 5.6 \times 10^{-6}\text{ A} = 0.0000056\text{ A}$$

Conversion of $2.3\text{ MW}$ to watts (W)

$$2.3\text{ MW} = 2.3 \times 10^6\text{ W} = 2\,300\,000\text{ W}$$

Conversion of $480\text{ nm}$ to metres (m)

$$480\text{ nm} = 480 \times 10^{-9}\text{ m} = 4.8 \times 10^{-7}\text{ m}$$

Conversion of $0.012\text{ A}$ to milliamps (mA)

$$0.012\text{ A} = 0.012 \times 1000 = 12\text{ mA}$$

Conversion of $15\,000\text{ Pa}$ to kilopascals (kPa)

$$15\,000\text{ Pa} = 15\,000 \div 1000 = 15\text{ kPa}$$

Conversion of $6.4 \times 10^6\text{ Hz}$ to megahertz (MHz)

$$6.4 \times 10^6\text{ Hz} \div 10^6 = 6.4\text{ MHz}$$

Conversion of $25\text{ mV}$ to volts (V)

$$25\text{ mV} = 25 \div 1000 = 0.025\text{ V}$$

Conversion of $5.0\text{ m}^2$ to $\text{cm}^2$

$1\text{ m}^2 = 100^2 = 10\,000\text{ cm}^2$, so $5.0\text{ m}^2 = 5.0 \times 10\,000 = 50\,000\text{ cm}^2$

Conversion of $2500\text{ cm}^3$ to $\text{m}^3$

$1\text{ m}^3 = 100^3 = 1\,000\,000\text{ cm}^3$, so $2500\text{ cm}^3 = 2500 \div 1\,000\,000 = 0.0025\text{ m}^3$ ($2.5 \times 10^{-3}\text{ m}^3$)

Conversion of $90\text{ km/h}$ to $\text{m/s}$

$$90\text{ km/h} = 90 \times 1000\text{ m} \div 3600\text{ s} = 90\,000 / 3600 = 25\text{ m/s}$$

Conversion of $15\text{ m/s}$ to $\text{km/h}$

$$15\text{ m/s} = 15 \times 3600 \div 1000 = 54\,000 / 1000 = 54\text{ km/h}$$

Conversion of Density: $8900\text{ kg/m}^3$ to $\text{g/cm}^3$

$8900\text{ kg/m}^3 = 8900 \times 1000\text{ g} \div 1\,000\,000\text{ cm}^3 = 8900 / 1000 = 8.9\text{ g/cm}^3$ ($\times 1000$ for $\text{kg} \rightarrow \text{g}$, $\div 1\,000\,000$ for $\text{m}^3 \rightarrow \text{cm}^3$; net factor is $\div 1000$)

Conversion of Density: $0.85\text{ g/cm}^3$ to $\text{kg/m}^3$

$$0.85\text{ g/cm}^3 = 0.85 \times 1000\text{ kg/m}^3 = 850\text{ kg/m}^3$$

Volume Calculation with Consistent Units ($2\text{ m} \times 50\text{ cm} \times 30\text{ cm}$)

Convert all dimensions to metres: $2\text{ m}$, $0.50\text{ m}$, $0.30\text{ m}$; Volume = $2 \times 0.50 \times 0.30 = 0.30\text{ m}^3$

Assessment Grade Boundaries (Out of $55\text{ marks}$)

Grade A: $\ge 47$; Grade B: $\ge 41$; Grade C: $\ge 36$; Grade D: $\ge 30$; Grade E: $\ge 25$