Chapter+4

=Chapter 4 Review=

Facts:

 * Work is the product of the force and the displacement in the direction of the force
 * One joule is the work done by a force of one newton applied via a displacement of one meter in the direction of the force
 * The area beneath a force-displacement graph represents the work done
 * Energy is the ability to do work and, like work, is measured in joules
 * Energy can be stored, transfered from object to object, and converted from one form to another
 * Energy is measured in terms of the work done
 * Gravitational potential energy depends on mass, gravitational field intensity, and vertical height
 * Kinetic energy depends on mass and speed
 * According to the law of conversation of energy, energy is neither created nor destroyed

Definitions:
__**chemical energy:**__ Potential energy stored in molecules

__**elastic energy:**__ Energy stored in an object when it is forced out of its normal shape

__**electrical energy (Ee):**__ Energy associated with moving electrical charges

__**energy (E):**__ Ability to do work

__**gigajoules (GJ):**__ One billion joules (J)

__**gravitional energy:**__ Energy associated with the gravitational field.

__**heat energy:**__ Energy that is transferred by a difference in temperature

__**joule (J):**__ Work done by a force of one newton applied via a displacement of one metre in the direction of the force; one joule equals one newton x meter

__**kilojoule (kJ):**__ One thousand joules.

__**kilowatt hour:**__ kW x h, common unit for electrical energy based on the relation deltaE= P x deltat where power is measured in kilowatts and time in hours; 1kW x h = 3.6 mega joules (MJ)

__**kinetic energy (Ek):**__ Energy of a moving object.

__**law of conservation of energy:**__ Energy cannot be created or destroyed; it can be changed from one form to another, but the total amount of energy in the universe stays constant.

__**megajoule (MJ):**__ One million joules

__**nuclear energy:**__ Energy stored in the nucleus of an atom

__**potential energy:**__ The energy of a body or system as a  result of its position in an electric, magnetic, or gravitational field.

__**radiant energy:**__ Energy that travels as electromagnetic waves

__**relative gravitional energy:**__

__**rest mass energy:**__

__**sound energy:**__ Energy that is carried from molecule to molecule by longitudinal vibrations

__**thermal energy:**__ Sum of the potential energy and the kenitic energy possessed by the molecules of an object

__**work (W):**__ Product of the magnitude of the applied force and the displacement of the object in the direction of the force

Formulas:
Work = (magnitude of the force in the direction of the displacement) x(magnitude of the displacement) The SI unit of the work is in newton metre (N.m), One joule (J) is work done by a force of one newton (N) applied via a displacement of one meter in the direction of the force: 1J = 1N.m
 * W = Fcos 0 delta//d//**
 * F is the magnitude of the force
 * delta//d is the magnitude of the displacement//
 * 0 is the angle between the force and the displacement
 * If the applied force is in the same direction as the displacement then the angle 0 is zero, if this is the case then the formula is simplified into W = F delta//d//

(Ex. 3) If objects are raised or lowered, the gravitional field intensity (9.8 N/kg [down]) comes into play. A force equal in magnitude to the force of gravity is needed to lift or lower the box at constant velocity. The magnitude of the force of ravity on the box is given by the eq'n FG = mg W = FGdelta//d, W =// mg delta//d//

__//Rest Mass Energy//__
It is the total energy that an object has because of its mass. Einstein's theory of relativity indicates that mass is a form of energy. This means that any mass has energy simply because the mass exists. The total energy of a mass at rest is given by the eq'n E = mc2 (squared)
 * E is the energy in joules, m is the mass in kilograms, and c is the speed of light in m/s

(P. 159) The work done on a mass is W = F delta//d,// W = FG delta//h,// W = mg delta//h// Assuming no friction, the work done is equal to the change in gravitional energy. Thus, the eq'n for the change in gravitational energy is deltaEG = mg delta//h//
 * Where m is the mass of the object in kilograms
 * g is the gravitational field intensity in newtons per kilogram
 * delta//h// is the magnitude of the vertical displacement of the object in metres
 * deltaEG is the change in gravitational energy of the object in joules

__Kenitic Energy (P. 163)__ W = ma delta//d// W = m(v2/delta//t//) (v2/2)delta//t// //W = 1/2m(v2)2 (squared)// //EK = 1/2mv2 (squared) -// m is the mass of the object in kilograms, v is the velocity of the object in metres per seacond, EK is the kenetic energy of the object in joules

(Ex. 11) __Conservation of energy=__ deltaEK = deltaEG and solve for v

__Kinematics=__ delta//d// = 1/2g(delta//t//)2 (squared), delta//t =// square root 2 delta//d/g//, v2 = g delta//t//