A harmonic wave travels in the positive x direction at 11 m/s along a taught strong. A fixed point on the string oscillates as a function of time according to the equation y=0.024 cos(3t) where y is the displacement in meters and the time t is in seconds.
What is the frequency of the wave in hertz? Frequency =

change tension

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

i don't understand. explain it clearly

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.