A force, such as friction, that operates opposite the direction of motion of a body and tends to prevent or slow down the body's motion. A measure of the degree to which a substance impedes the flow of electric current induced by a voltage. Resistance is measured in ohms.
What is a tornado? A tornado is a violent rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of up to 300 mph. They can destroy large buildings, uproot trees and hurl vehicles hundreds of yards. They can also drive straw into trees.
How a Tornado Forms. Thunderstorm-. The first thing that is needed to produce a tornado is a thunderstorm. To create a thunderstorm you need to have three things, the first of which is a mass of unstable air, which is the result of warm moist air in the lower atmosphere and cold dry air in the upper atmosphere.