12 - Mechanical Waves and Sound Free Online FlashCards

What is a mechanical wave?

A mechanical wave is a traveling disturbance that requires a material medium and transfers energy and momentum through it.

What do particles do as a mechanical wave passes?

The particles generally oscillate around equilibrium positions while the wave transfers energy and momentum through the medium.

How are frequency and period related?

Frequency is the number of cycles per second, while period is the time for one cycle. They satisfy $f=\frac{1}{T}$.

What equation relates wave speed, frequency, and wavelength?

For a periodic wave, wave speed equals frequency times wavelength: $v=f\lambda=\frac{\lambda}{T}$.

How is a transverse wave defined?

In a transverse wave, particles oscillate perpendicular to the direction of wave propagation.

How is a longitudinal wave defined?

In a longitudinal wave, particles oscillate parallel to the direction of wave propagation.

Which sign indicates positive wave travel?

In $y(x,t)=A\sin(kx-\omega t+\phi)$, the $kx-\omega t$ combination represents motion in the positive $x$-direction.

What determines wave speed on a stretched string?

For a stretched string, wave speed is $v=\sqrt{\frac{F_T}{\mu}}$. Greater tension increases speed; greater linear mass density decreases it.

What is the principle of superposition?

The resultant displacement equals the algebraic sum of the individual displacements: $y_{\text{resultant}}=y_1+y_2+y_3+\cdots$.

How is beat frequency calculated?

The beat frequency is the absolute difference between the two frequencies: $f_{\text{beat}}=|f_1-f_2|$.

What are nodes and antinodes in a standing wave?

A standing wave has nodes with zero displacement and antinodes with maximum amplitude. Adjacent nodes are separated by $\lambda/2$.

What are the allowed frequencies of a fixed-end string?

For a string fixed at both ends, allowed frequencies are $f_n=\frac{nv}{2L}$, where $n=1,2,3,\ldots$.