Steam

Steam is water in the gas phase, which is formed when water boils. Steam is invisible; however, "steam" often refers to wet steam, the visible mist or aerosol of water droplets formed as this water vapor condenses. At lower pressures, such as in the upper atmosphere or at the top of high mountains, water boils at a lower temperature than the nominal 100 °C (212 °F) at standard temperature and pressure. If heated further it becomes superheated steam.

The enthalpy of vaporization is the energy required to turn water into the gaseous form when it increases in volume by 1,700 times at standard temperature and pressure; this change in volume can be converted into mechanical work by steam engines such as reciprocating piston type engines and steam turbines, which are a sub-group of steam engines. Piston type steam engines played a central role to the Industrial Revolution and modern steam turbines are used to generate more than 80% of the world's electricity. If liquid water comes in contact with a very hot surface or depressurizes quickly below its vapor pressure, it can create a steam explosion. Steam explosions have been responsible for many foundry accidents, and may also have been responsible for much of the damage to the plant in the Chernobyl disaster.

Collision

A collision is an event in which two or more bodies exert forces on each other for a relatively short time. Although the most common colloquial use of the word "collision" refers to incidents in which two or more objects collide, the scientific use of the word "collision" implies nothing about the magnitude of the force.

Some examples of physical interactions that scientists would consider collisions:

Some colloquial uses of the word collision are:

Overview

Collision is short-duration interaction between two bodies or more than two bodies simultaneously causing change in motion of bodies involved due to internal forces acted between them during this. Collisions involve forces (there is a change in velocity). The magnitude of the velocity difference at impact is called the closing speed. All collisions conserve momentum. What distinguishes different types of collisions is whether they also conserve kinetic energy. Line of impact – It is the line which is common normal for surfaces are closest or in contact during impact. This is the line along which internal force of collision acts during impact and Newton's coefficient of restitution is defined only along this line.

Collision course

A collision course, also known as a kamikaze run, is the deliberate maneuver by the operator of a moving object (or often in Sci-Fi a spaceship) to collide with another object. It is a desperate maneuver since it often damages or destroys both.

Uses in history

Steam locomotive

A steam locomotive is a railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible material—usually coal, wood, or oil—to produce steam in a boiler. The steam moves reciprocating pistons which are mechanically connected to the locomotive's main wheels (drivers). Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons (tenders) pulled behind. The first steam locomotive, made by Richard Trevithick, first operated on 21 February 1804, three years after the road locomotive he made in 1801.

Steam locomotives were first developed in Great Britain during the early 19th century and dominated railway transport until the middle of the 20th century. From the early 1900s they were gradually superseded by electric and diesel locomotives, with full conversions to electric and diesel power beginning from the 1930s. The majority of steam locomotives were retired from regular service by the 1980s, though several continue to run on tourist and heritage lines.

California

California (ⁱ/ˌkælᵻˈfɔːrnjə/ KAL-ə-FORN-yə, /ˌkælᵻˈfɔːrniə/ KAL-ə-FAWR-nee-ə) is a state located on the West Coast of the United States. It is the most populous U.S. state, with 39 million people, and the third largest state by area (after Alaska and Texas). California is bordered by Oregon to the north, Nevada to the east, Arizona to the southeast, and the Mexican state of Baja California to the south. It contains the nation's second most populous census statistical area (Greater Los Angeles Area) and the fifth most populous (San Francisco Bay Area), and eight of the nation's 50 most populated cities (Los Angeles, San Diego, San Jose, San Francisco, Fresno, Sacramento, Long Beach, and Oakland). Sacramento has been the state capital since 1854.

What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries. It was then claimed by the Spanish Empire as part of Alta California in the larger territory of New Spain. Alta California became a part of Mexico in 1821 following its successful war for independence, but was ceded to the United States in 1848 after the Mexican–American War. The western portion of Alta California was organized as the State of California, which was admitted as the 31st state on September 9, 1850. The California Gold Rush starting in 1848 led to dramatic social and demographic change, with large-scale immigration from the east and abroad with an accompanying economic boom.