physical quantities and units

Question

Which pair correctly represents a derived physical quantity and its SI unit?

RankGuru · Accepted Answer

1. **Power**: Defined as the rate of doing work ($P = W/t$). Since work is measured in Joules ($J$) and time in seconds ($s$), the SI unit is $J/s$ or $J \cdot s^{-1}$, also known as the **Watt ($W$)**.
2. **Pressure**: $P = F/A$. SI unit is $N/m^2$ or Pascal ($Pa$), not $N \cdot m$.
3. **Energy**: SI unit is the Joule ($J$), which is $N \cdot m = (kg \cdot m \cdot s^{-2}) \cdot m = kg \cdot m^2 \cdot s^{-2}$.
4. **Momentum**: $p = mv$. SI unit is $kg \cdot m \cdot s^{-1}$.

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physical quantities and units

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