The faster a sound wave travels, the more distance it will cover in the same period of time. If a sound wave were observed to travel a distance of 700 meters in 2 seconds, then the speed of the wave would be 350 m/s. A slower wave would cover less distance-perhaps 660 meters-in the same time period of 2 seconds and thus have a speed of 330 m/s.
Melanoma Definition. Melanoma is a form of skin cancer that arises from melanocytes-the cells that produce pigment. Melanoma may begin in association with a mole. Melanocytes produce a pigment called melanin that gives the skin its colour and protects it from sun damage.
Melanoma: Causes, Symptoms and Treatments. Melanoma is not the most common type of skin cancer, but it is the most serious. There are many risk factors for melanoma, including one major risk factor that is largely avoidable - overexposure to the sun.