The danger of pyroclastic flow comes from its speed and heat. According to Michigan Technological University, pyroclastic flows have reached extreme high temperatures, including flows from the Mt. Pelee eruption that got... More »

Pyroclastic flows are enormous ejections of debris from erupting volcanoes. They consist of large rocks and smaller particles of ash and dust that travel across the surrounding landscape at tremendous velocity. More » Science Earth Science Volcanoes

Pyroclastic flows travel away from a volcano's vent at speeds up to 150 kilometers per hour. They contain hot gas, ash and rock at temperatures ranging from 100 to 800 degrees Celsius. More » Science Physics Thermodynamics

Instantaneous speed refers to the speed of an object at a specific point in time. Most speeds are average speeds, which is calculated by dividing the distance traveled by the time it took to travel it. More » Science Physics Motion & Mechanics

As of 2014, the fastest rocket ship, NASA's New Horizons spacecraft, was recorded at a speed of 36,000 miles per hour. The speed a spacecraft travels depends on if it is ascending, orbiting or returning to Earth. More »

Acceleration is any change in the speed or the direction of movement. It does not matter, from a scientific point of view, if only the direction changes but not the speed, as with a planet in a circular orbit, or if the ... More »

The "slingshot effect" is a term for a space probe or ship using the speed of a planetary body in order to build the speed of the probe. This requires launching the probe at the right time so that the planet's rotation l... More » Science Physics Motion & Mechanics