“Stationary waves” are so called because in them

From which condition are the normal modes for the case of small hand drums decided?

$A$ wave travels on a light string. The equation of the wave is $Y = A \sin (kx - \omega t + 30^o)$. It is reflected from a heavy string tied to an end of the light string at $x = 0$. If $64\%$ of the incident energy is reflected,the equation of the reflected wave is:

$A$ standing wave having $3$ nodes and $2$ antinodes is formed between two atoms having a distance of $1.21 \ Å$ between them. The wavelength of the standing wave is (in $Å$)

Two sinusoidal waves with same wavelengths and amplitudes travel in opposite directions along a string with a speed $10 \, ms^{-1}$. If the minimum time interval between two instants when the string is flat is $0.5 \, s$,the wavelength of the waves is .... $m$

The velocity of waves in a string fixed at both ends is $2 \ m/s$. The string forms standing waves with nodes $5.0 \ cm$ apart. The frequency of vibration of the string in $Hz$ is