My tenth grade physics textbook says that sound travels faster in solids than air. But it also says sound will travel faster in air if its density decreases. I didn't really get the logic, as solids are denser than air, and that is why sound travels faster. Then they say as temperature of air increases , sound will travel faster in it as its density decreases. Can anyone please explain this? They have also given this formula: Velocity of sound = root of elasticity divided by root of density of medium.
according to the given equation, V= √(E/d) a lower density will give you a bigger number under the radical and hence a bigger velocity. but in regards to your confusion of higher density = faster speed of sound and lower density = lower speed of sound - this is untrue, its not the density is not directly proportional to the speed of sound, but the tension is directly proportional to the speed of sound, here is a thread that discusses in more detail: https://www.physicsforums.com/showthread.php?t=206667