Question

A copper rod is given a sharp compressional blow at one end. The sound of the blow, traveling through air at −1.34 ◦C, reaches the opposite end of the rod 3.18 ms later than the sound transmitted through the rod. What is the length of the rod? The speed of sound in copper is 3160 m/s and the speed of sound in air at −1.34 ◦C is 331 m/s. Answer in units of m.

Answer 1

b

Step-by-step explanation:

Answer 2

Step-by-step explanation:

The speed of sound in copper,
`v_c=3160\ m/s`

The speed of sound in air at 1.34°C,
`v_a=331\ m/s`

The sound of the blow, traveling through air, reaches the opposite end of the rod 3.18 ms later than the sound transmitted through the rod. Time difference,
`\Delta t=3.18\ m/s=3.18* 10^(-3)\ m`

Since,
`time=(distance)/(speed)`

`\Delta t=(l)/(v_a)-(1)/(v_c)`

`3.18* 10^(-3)=(l)/(331)-(1)/(3160)`

l = 1.17 meters

So, the length of the rod is 1.17 meters. Hence, this is the required solution.