i think it would be 80 km/h because 30 + 50 = 80 (sorry if this not the right answer i'm trying my best)
well a basic explanation is that some elements have enough electrons to be considered stable. these elements do not need to react with other elements to gain more electrons. reactive elements are no where near stable; they respond with other elements in order to become stable. the more unstable, the harsher the reaction is.
kinetic energy because the bird is in motion
the first one is high roller, the second one is singapore flyer, the third one is giant wheel.