MCQ
A person standing between two vertical cliffs and 640m away from the nearest cliff shouted. He heard the first echo after 4 seconds and the second echo 3 seconds later. What is the distance between the cliffs?
- A1570m
- B1760m
- C1520m
- D1225m
Explanation:
$\text{v}=\frac{2\text{d}}{\text{t}}$
$\Rightarrow\text{v}=\frac{2\times640}{4}=320\text{m/ s}$
$\therefore\text{v}=\frac{2\text{d}}{\text{t}}$
$\Rightarrow320=\frac{2\text{x}}{7}$
$\text{x}=1120\text{m}$
Distance $=1120+640$
$=1760\text{m}$
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