Question

An echo is heard by a radar in 0.08 s. If velocity of radio waves is 3 × 10⁸ ms⁻¹, how far is the enemy plane?

Answer 1

Given t = 0.08 s; v = 3 × 10⁸ ms⁻¹

Now, velocity of radio waves \[= \frac{2d}{t} \]

\[ \therefore 3 \times 10^{8} \ \mathrm{ms^{-1}} = \frac{2 \times d}{0.08 \ \text{s}} \]

\[ \therefore d = \frac{3 \times 10^{8} \times 0.08}{2} \ \text{m} \]

∴ d = 1.2 × 10⁷ m

∴ d = 12000 km