Question

A radar sends a signal to an aircraft at a distance of $30km$ away and receives it back after $2\times {10}^{-4}$ second. What is the speed of the signal?

Answer 1

Given: Distance of aircraft $=30km=30,000m$
Total distance $=2\times 30,000=60,000m$
Time taken $=2\times {10}^{-4}second$
Hence Speed of signal $\left(V\right)=\frac{\text{Total distance travelled}\left(2d\right)}{\text{time taken}\left(t\right)}$
$=\frac{60,000}{2\times {10}^{-4}}=30,000\times {10}^{4}m/s$
$=3\times {10}^{8}m/s$.

Therefore, the speed of the signal is $3\times {10}^{8}m/s$.