Humans have two kidneys and each kidney is supplied with blood from the renal artery. The kidneys remove from the blood the nitrogenous wastes such as urea, as well as salts and excess water, and excrete them in the form of urine.This is done with the help of millions of nephrons present in the kidney.umans have two kidneys and each kidney is supplied with blood from the renal artery. The kidneys remove from the blood the nitrogenous wastes such as urea, as well as salts and excess water, and excrete them in the form of urine.
This is because the speed of sound waves depends upon the material through which they are travelling. Sound travels 15 times faster through the metal railway tracks than through air, giving the cowboy an early warning of the train's arrival. How much plainer could it be? I, personally, had never thought of it that way. I love this illustration.
Sound waves need to travel through a medium such as a solid, liquid, or gas. The sound waves move through each of these mediums by vibrating the molecules in the matter. The molecules in solids are packed very tightly.Liquids are not packed as tightly as solids.And gases are very loosely packed. The spacing of the molecules enables sound to travel much faster through a solid than a gas. Sound travels about four times faster and farther in water than it does in air.This is why whales can communicate over huge distances in the oceans. Sound waves travel about thirteen times faster in wood than air.iquids are not packed as tightly as solids. And gases are very loosely packed. The spacing of the molecules enables sound to travel much faster through a solid than a gas. Sound travels about four times faster and farther in water than it does in air.