91Ó°ÊÓ

1. Pressure of tire,$p_t=28psi\mathrm{or}28lb/i{n}^2$

1. High and low blood pressure,$p_b=120mmHg$and$80mmHg$

We can use the dimensional analysis concept to find the pressure in tire and blood in kPa. Using conversion factors between psi$\mathit{l}\mathit{b}\mathbf{/}\mathit{i}{\mathit{n}}^{\mathbf{2}}$ and$\mathit{l}\mathit{b}\mathbf{/}\mathit{i}{\mathit{n}}^{\mathbf{2}}$ between Pa and , we can findthepressure in the tire in kPa. Then using the conversion factor between mm Hg and Pa, we can find the blood pressure in kPa.

Formula:

Pressure on a body by force F on an area A,

$p=\frac{F}{A}$ (i)

$$\begin{gathered} p_t=28lb/i{n}^2×\frac{1.01×{10}^{5}Pa}{14.7lb/i{n}^2}\left(âˆ\mu 1atm=1.01×{10}^{5}Pa=lb/i{n}^2\right) \\ =192.4kPa \end{gathered}$$ Hence, the tire pressure value is 192.4 kPa.

Calculation for 120 mmHg:

$$\begin{gathered} p_b=120mmHg×\frac{1.01×{10}^{5}Pa}{760mmHg}\left(âˆ\mu 1atm=1.01×{10}^{5}Pa=lb/i{n}^2\right) \\ =15.9kPa \end{gathered}$$Calculation for 80 mmHg:

$$\begin{gathered} p_b=80mmHg×\frac{1.01×{10}^{5}Pa}{760mmHg}\left(âˆ\mu 1atm=1.01×{10}^{5}Pa=lb/i{n}^2\right) \\ =10.6kPa \end{gathered}$$ Hence, the blood pressure values are 15.9 kPa and 10.6 kPa for 120mmHg and 80mmHg respectively.