I'll try to explain, because I've had tubes before. In fact, I still have them.
For me, tubes were put in because of too many ear infections, and excessive water in my ear. The tube helped drain the water out. You can see A picture I have in a file. The tubes can be put I believe in the ear drum. They're put there to help drain water that has trouble getting out on its own.
A distance-time graph is graph that represents the speed of an object and the velocity of an object is its speed in a particular direction.
A velocity-time graph is a graph that represents the acceleration or velocity of an object.
A wind-velocity diagram is a diagram that measures wind<span> speed, or </span>wind flow velocity.
A HR Diagram (Hertzsprung-Russell Diagram) is<span> a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their spectral classifications or effective temperatures.
Hope this helps!</span>