Physics Laboratory Experiments

Jerry D. Wilson, Cecilia A. Hernandez-Hall

Chapter 17 Standing Waves in a String - all with Video Answers

Educators

Chapter Questions

Problem 1

The length, $L_{1}$, is not the wavelength of the fundamental frequency of the string.
(a) With the tension equal to $F_{1}$, to which natural frequency does the wavelength equal to $L_{1}$ correspond?
(b) What tension in the string would be required to produce a standing wave with a wavelength equal to $L_{1}$ ? (Hint: Use Eq. 17.7.)

Supratim Pal

Numerade Educator

02:26

Problem 2

Theoretically, the vibrator frequency is $120 \mathrm{~Hz}$. However, sometimes the vibrator resonates with the string at a "subharmonic" of $60 \mathrm{~Hz}$.
(a) If this were the case in all instances, how would it affect the slope of the graph?
(b) If you have some scattered data points far from the straight line on your graph, analyze the data for these points using Eq. $17.7$ to determine the frequency.

Mayukh Banik

Numerade Educator

08:08

Problem 3

How many normal modes of oscillation or natural frequencies does each of the following have: (a) a simple pendulum, (b) a clothes line, and (c) a mass oscillating on a spring?

Khoobchandra Agrawal

Numerade Educator

01:08

Problem 4

Stringed musical instruments, such as violins and guitars, use stretched strings. Explain
(a) how tightening and loosening the strings tunes them to their designated tone pitch or frequency; (b) why the strings of lower tones are thicker or heavier; and
(c) why notes of higher pitch or frequency are produced when the fingers are placed on the strings.

Ma Ednelyn Lim

Numerade Educator

00:51

Problem 5

(Optional) Consider a long whip antenna of the type used on some automobiles and trucks. Show that the natural frequencies of oscillation for the antenna are $f_{\mathrm{m}}=m v / 4 L$, where $m=1,3,5, \ldots, v$ is the wave speed, and $L$ is the length of the antenna. (Hint: The boundary conditions are a node and an antinode.)

Mayukh Banik

Numerade Educator