At a particular time of the day, a vertical wooden rod of length $15\text{ cm}$ casts a shadow $30\text{…
At a particular time of the day, a vertical wooden rod of length $15\text{ cm}$ casts a shadow $30\text{ cm}$ long on flat ground. At the same time and place, a vertical metal pole casts a shadow $120\text{ cm}$ long. What is the height of the metal pole?
$60\text{ cm}$
$240\text{ cm}$
$90\text{ cm}$
$45\text{ cm}$
Solution
Under the same sun position, the ratio of object height to shadow length is constant ($15 : 30 = 1 : 2$). Therefore, a shadow length of $120\text{ cm}$ corresponds to an object height of $120 \div 2 = 60\text{ cm}$.