Question: A chemist’s 50-Trillion Angstrom Run (see Exercise 1.78) would be an archeologist’s 10,900 cubit run. Howlong is one cubit in meters and in feet? (1 Å = 1 × 10^-8 cm)

We know that one trillion Angstrom is equal to 5 km (from Exercise 1.78).

A cubit is an ancient measure unit. It is measured based on the length between the elbow to the middle finger.

Also, 10,900 cubits are considered 50 Trillion Angstrom.

We know that

\(\begin{array}{c}50\,\,trillion\,Angstrom\,\, = \,\,\,50\,\, \times \,\,{10^{12}}\, \times \,{10^{ - 10}}\,m\,\\\, = \,\,5000\,\,m\\\,\, = \,\,5\,\,km\end{array}\)

And

\(10,900\,\,cubit\,\, = \,\,\,50\,trillion\,\,Angstrom\)

Therefore,

\(10,900\,\,cubit\,\, = \,\,5000\,\,m\)

\(\begin{array}{l}1\,\,cubit\,\, = \,\,\frac{{5000}}{{10,900}}\,\,m\,\,\\1\,\,cubit\,\, = \,\,\,0.4587\,\,m\end{array}\)

Rounding off, we get 0.46 m.

Also, we know

\(1\,\,m\,\, = \,\,3.28\,\,ft\)

We get

\(\begin{array}{c}1\,\,cubit\,\, = \,\,0.4587\,\,m\,\\\, = \,\,1.5049\,\,ft\end{array}\)

Rounding off, we get 1.5 ft.

Therefore, one cubit in meters and feet are 0.46 m and 1.5 ft.