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.
Chuck Yeager and the X-1 research plane that broke the sound barrier in 1947. It can be seen today at the Smithsonian Air & Space Museum in Washington, D.C. The speed of sound varies depending on the temperature of the air through which the sound moves. On Earth, the speed of sound at sea level â assuming an air temperature of 59 degrees Fahrenheit (15 degrees Celsius) â is 761.2 mph (1,225 km/h). Because gas molecules move more slowly at colder temperatures, that slows the speed of sound; sound moves faster through warmer air.