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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 forces. Some examples of physical interactions that scientists would consider collisions: * An insect touches its antenna to the leaf of a plant. The antenna is said to collide with leaf. * A cat walks delicately through the grass. Each contact that its paws make with the ground is a collision. Each brush of its fur against a blade of grass is a collision. Some colloquial uses of the word collision are: * automobile collision, two cars colliding with each other * mid-air collision, two planes colliding with each other * ship collision, two ships colliding with each other ==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. Specifically, collisions can either be ''elastic,'' meaning they conserve both momentum and kinetic energy, or ''inelastic,'' meaning they conserve momentum but not kinetic energy. An inelastic collision is sometimes also called a ''plastic collision.'' A “perfectly inelastic” collision (also called a "perfectly plastic" collision) is a limiting case of inelastic collision in which the two bodies stick together after impact. The degree to which a collision is elastic or inelastic is quantified by the coefficient of restitution, a value that generally ranges between zero and one. A perfectly elastic collision has a coefficient of restitution of one; a perfectly inelastic collision has a coefficient of restitution of zero. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「collision」の詳細全文を読む スポンサード リンク
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