Jason is swimming in his backyard pool and notices that sounds underwater are different than sounds above water. what best explains the difference in sounds?

-the difference between how air flows and water flows
-water entering jason's ears and blocking sounds
-interactions between sound waves and light waves
-the different speed of sound waves in water and in air

The different speed of sound waves in water and in air

Explanation:

In general, sound (which is a mechanical wave) travels faster in solids than in liquids or gases. This is because the speed of  mechanical waves is determined by a relationship between the elastic properties of the medium in which they are propagated and the mass per unit volume of the medium (that is: density).  

In other words: The speed of sound varies depending on the medium through which the sound waves travel.  

This is why Jason notices that sounds underwater (a liquid medium) are different from sounds above water (a gas medium: air).

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explanation:

the velocity you are looking for is made up of two parts: horizontally velocity, vh, and its vertical velocity, vv. the actual velocity of the ball will be these two parts added together, and because velocity is a vector then they will need to be added vectorially.  

neglecting air resistance etc etc.,  

the horizontal velocity component will be constant (because there is no accelerating force in the horizontal direction.  

vh = 8 ms-1  

the vertical velocity component has an accelerating force: 'g'.  

using v = u +at where a = g = 9.81 ms-2.  

the vertical component of velocity, vv = 0 + gt = vv =9.81 x 2  

vv = 19.62 ms-1 . the zero appears because the virtical component of velocity at time t=0 is zero. remember, the ball was thrown horizontally.  

how fast it will be moving (it actual path (being a parabola )) will be the vector sum of these two.  

adding vectorally gives: -  

v = sqr root (8^2 + 19.62^2) = sqr root(64+384.9) = 21.18 or 21.2 ms-1