I believe a valley or mountain, but I am not 100 percent sure.
Answer:
If we are watching the sky, we see the lightning before we hear the thunder. That is because light travels much faster than sound waves. We can estimate the distance of the lightning by counting how many seconds it takes until we hear the thunder. It takes approximately 5 seconds for the sound to travel 1 mile.
Explanation:
The invention of microscopes changed the way cells were able to reproduce.
The heart, blood vessels and blood itself are three essential components the body needs to survive. The circulatory system consists of two circuits that blood travels through; pulmonary and systemic.