Asteroids
An asteroid is a minor planet in the inner solar system, the term minor planet has historically been applies to any astronomical object orbiting the sun that did not show the disk of a planet. Asteroids supposedly don’t have the characteristics of an active comet but their volatile based surfaces resemble comets more closely than originally thought.(1) Whereas a meteorite is a small rocky or metallic body that travels through space, they are significantly smaller than asteroids and range in size from small grains to 1 meter-wide objects. Smaller objects than this are classified as micrometeoroids or space dust; most of these are fragments from comets or asteroids after a collision.(2) An impact crater is a hole excavated out of a surface usually circular (e.g. a planet, moon, asteroid, or comet) when a smaller mass moving at very high speed collides with it. Impact craters typically have raised rims and floors that are lower in elevation than the surroundings. Meteor crater is perhaps the best-known example of a small impact crater on the Earth. (3) The Barringer crater is over a kilometre in diameter and 750ft in depth.(4) The size and shape of the crater depends on factors such as the velocity and mass of the impacter and the surface it hits. The faster the incoming impacter, the larger the crater. (5) Because of physics the total amount of energy is conserved when two bodies strike each other. The energy can only be transferred and not lost. The large amount of energy goes into making several things happen: Melting or vaporizing material from the impacter and a lot of energy and momentum will go into moving the material. Some endothermic chemical reactions (ones which require energy) may be driven to occur, if they can happen fast enough, before the heat moves or vanishes. When an object with Gravitational Potential Energy starts to fall, its GPE is transferred into Kinetic Energy. The further the object falls, the less GPE it has and the more KE it has. When
Bibliography: https://solarsystem.nasa.gov/deepimpact/science/cratering.cfm (5) www.lpi.usra.edu (4) www.amusingplanet.com (3) http://en.wikipedia.org/wiki/Meteoroid (2) http://en.wikipedia.org/wiki/Asteroid (1)