Bal u fiirsada dhulka (sida xabaal leh \(r_1 = 6370km\) ) iyo digir ( sida goob leh \(r_2 = 2mm\) ) oo xadhig ku fidi dhulbaraha si uu si adag ugu jiifsado. Hadda labada xadhig ku kordhi midkiiba hal mitir. Labada fiilooyinka hadda waa inay si buuxda u jiifsadaan dhulbarbaraha - laakiin gabi ahaanba ma aha kuwa dusha sare saaran, laakiin waxay sabbeeyaan korka dhulbaraha. Intee in le'eg ayuu ka sarreeyaa dusha sare ee xadhiggu ka sarreeyaa dhulka, intee buu ka sarreeyaa digirta?
Labada xarig waxay marka hore leeyihiin dherer:
$$
l_1 = 2\cdot 6370 km \cdot \pi \Leftrightarrow r_1 = 6370 km = \frac{l_1}{2 \cdot \pi}
$$
sida
$$
l_2 = 2 \cdot 2mm \cdot \pi \Leftrightarrow r_2 = 2mm = \frac{l_2}{2 \cdot \pi}.
$$
Laakiin hadda waa kordhinta kadib
$$
r_{1 NEU} = \frac{l_1 + 1m}{2\cdot \pi}
$$
sida
$$
r_{2 NEU} = \frac{l_2 + 1m}{2\cdot \pi}.
$$
Laakiin hadda waa wax la yaab leh
$$
r_{1 NEU} - r_1 = \frac{l_1 + 1m}{2\cdot \pi} - \frac{l_1}{2\cdot \pi} = \frac{l_1 + 1m - l_1}{2 \cdot \pi} = \frac{1m}{2 \cdot \pi} = 0.159m
$$
sida
$$
r_{2 NEU} - r_2 = \frac{l_2 + 1m}{2\cdot \pi} - \frac{l_2}{2\cdot \pi} = \frac{l_2 + 1m - l_2}{2 \cdot \pi} = \frac{1m}{2 \cdot \pi} = 0.159m.
$$
Marka masaafada dusha sare ka madax banaan \(l_1\) ama \(l_2\) , \(l_2\) madax banaan raadiye \(r_1\) ama \(r_2\) qaybaha. Jawaabta yaabka leh ayaa ah sidan: Labada \(0.159m\) isla dhererka \(0.159m\) ) dusha sare.