Collisions

Collision occurs when two or more objects hit each other.

Kinds of Collision
     a. Elastic Collision - are collisions in which both momentum and kinetic energy are conserved. The total system kinetic energy before the collision equals the total system kinetic energy after collision.
  b. Inelastic collision - a collision in which the total kinetic energy after the collision is less than the collision.
   c. Complete inelastic - inelastic collision in which the colliding bodies stick together and move as one body after collision.

Newton's Law of Universal Gravitation

"Every particle attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distances between them".

F = GM./r^2
Gravitational constant: G= 6.67*10^-11 Nm^2/kg^2

Types of Organic Reactions

     Substitution Reaction (Single replacement reaction or single displacement reaction) . In this reaction a hydrogen atom or a functional group is replaced by a different functional group.To recognize this type of reaction, look for the following two features:

           • two compounds react to form two different compounds

           • carbon atoms bonded to the same number of atoms in the product as in the reactant

                                      ex. One group replaces another

      Addition Reaction. In this reaction atoms are added to a double or triple bond. To recognize an addition reaction, check whether the carbon atoms in the product(s) are bonded to more atoms than are the carbon atoms in the organic reactant.

ex. A molecule adds across a pi bond

      Elimination Reaction. In this reaction atoms are removed from an organic molecule and a double bond forms between the two carbon atoms from which the atoms were removed. This reaction can be envisioned as the reverse of an addition reaction. One reactant usually loses two atoms, and two products are formed. A double bond is formed in the organic product. To recognize an elimination reaction, determine whether the carbon atoms in the organic product are bonded to fewer atoms than were the carbon atoms in the organic reactant.

ex.

    Rearrangement Reaction. In this reaction the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule.

    Condensation Reaction. In this reaction two molecules combine to form a larger molecule, producing a small, stable molecule, usually water, as a second product or functional group.

    Esterification Reaction. This is a reaction of a carboxylic acid with an alcohol to form an ester and water; a specific type of condensation reaction. Esterification reactions can be used to produce useful consumer products, such as acetylsalicyclic acid, commonly sold as Aspirin. Many of the flavours and aromas of fruits and spices are due to the presence of esters. Through esterification reactions, chemists have learned to duplicate natural esters. Synthesized esters are used to give artificial flavour to juices, candy, and many foods.

ex.

     Hydrolysis Reaction is essentially the reverse of a condensation reaction. This reaction is a chemical process in which a certain molecule is split into two parts by the addition of a molecule of water.