Question

3. Two horns emit sounds of frequency 365 Hz and 371 Hz. What is their beat frequency?

4. An organ pipe manufacturer wants to make a pipe that resonates with a fundamental frequency of 32.75 Hz. Assume the speed of sound in air is 343 m/s. What must the length of the pipe be if it is

a. an open pipe?

c. a closed pipe?

Answer 1

3.

$$f_b=371-365=6\ Hz$$

4.

a.

$$l=\frac{v}{2f}=\frac{343}{2\cdot 32.75}=5.24\ m$$

b.

$$l=\frac{v}{4f}=\frac{343}{4\cdot 32.75}=2.62\ m$$