"Frequency" means how often something happens. When you say how many times it happens every SECOND, you can call the number Hertz, or Hz.
In the graph, there are 10 vibrations in 10 seconds, 20 of them in 20 seconds, and 30 in 30 seconds. This should pretty much shout at you "THERE'S ONE VIBRATION EVERY SECOND !". When you realize that, you can say the frequency of the vibration is 1 Hz.
The graph tells us nothing about the speed of the waves. I suspect there's another picture to the question that you didn't include. If the other part shows the wavelength, then we could figure out the speed. But with just what you're showing us, we can't.
<span>PV is actually energy. P = F/A force per area, and V = A L, so PV = F L and force times distance is work which is energy. If you have P in N/m^2 and V in m^3, you have Joules, N-m.</span>
They do not demonstrate Earth's tilt. In fact, they're not "used" to demonstrate anything. It works the other way:. When you observe the Coriolis effect and the behavior of the Foucault pendulum, and you try to explain why the behave the way they do, one possible simple explanation for both of them is the Earth's ROTATION. Then, when you also observe the rising and setting of the sun and moon, and you also notice how the NUMBERS all go together, the case for the rotating, spherical Earth gets stronger and stronger.
The correct answer to the question is : Transverse wave.
EXPLANATION :
Before going to answer this question, first we have to understand the longitudinal and transverse wave.
LONGITUDINAL WAVE : A longitudinal wave is a mechanical wave in which the direction of vibration of particles is parallel to the direction of wave propagation. It moves in the form of compression and rarefaction.
For instance, sound wave.
TRANSVERSE WAVE : A transverse wave is a mechanical wave in which the direction of vibration of particles is perpendicular to the direction of wave propagation. It moves in the form of crests and troughs.
For instance, the wave created in a pond when a stone is dropped into it.
Hence, the correct answer of this question is transverse wave.