Chapter 10, Problem 12STP

To determine

The duration after which `the sound will reach the ear.

Answer to Problem 12STP

Thetime taken is, $\boxed{t=0.2\text{ s}}$ .

Explanation of Solution

Given:

The speed of sound in iron is 5100 m/s and the distance of the sound travelled is 510 m.

Formula used:

The expression for time, speed and distance is,

  $v=\frac{d}{t}$…… (1)

Here, v is the speed of sound, d is the distance travelled by the sound and t is the time taken.

Since for an echo to be recorded it has to travel towards the object and reflect back to source and is given as d =2× d.

Calculation:

Substituting 5100 m/s second in v and 2× 510 m in d in equation (1),

  $\begin{array}{l}5100=\frac{2\times 510}{t}\\ \boxed{t=0.2\text{ s}}\end{array}$

Conclusion:

Hence, the time taken is, $\boxed{t=0.2\text{ s}}$ .