ENERGY

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Energy: Is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.

LAWS OF CONSERVATION OF ENERGY: The law of the conservation of energy states that the energy can neither be created nor destroyed. Only converted from one form of energy to another.

Applications: (1) when the pendulum swings upwards, the kinetic energy is converted to potential energy. (2) When the water falls from the sky, It converts potentials energy to kinetic energy.

Types of Energy

Kinetic energy:Is a property of a moving object or particle and depends not only on its motion but also on its mass.

EXAMPLE: Moving car, Bullet from the gun, Flying Airplane. Formula: K.E=1/2m v2. UNIT: 1kg m2/s2.

ROTATIONAL KINECTIC ENERGY: Is the kinectic energy due to the rotational of an object and is the part of its total kinectic energy

TRANSATIONAL KINETIC ENERGY: A body is equal to one-half of the product of its mass,m and the square of its velocity.

VIBRATIONAL KINECTIC ENERGY: Is the kinetic energy an object has due to its vibrational motion.

Gravitational energy: or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity

FORMULA: PEg=mgh. EXAMPLE: A car that is parked at the top of the hill. UNIT: Newtons per kilogram (N/Kg)

Potential energy: the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.

EXAMPLE: Water that is behind a dam

UNIT: (Kgxm2s2)

FORMULA: U=m g h U = gravitational energy m = mass g = gravitational field h = height

Nuclear energy: is the energy in the nucleus, or core, of an atom. Nuclear energy can be used to create electricity.

EXAMPLE: The sun

UNIT: The mass defect of about 0.2 atomic mass units is converted into an energy of 210 MeV For an atomic mass unit, u, we have u ≈ 1.66 × 10−27 kg, and the atomic energy unit electron volt, eV, is about 1.60 × 10−19J

formula: E = mc2 explains this. The equation says: E [energy] equals m [mass] times c2 [c stands for the speed or velocity of light].

Chemical energy: Energy stored in the bonds of chemical compounds. Reactions that require an input of heat to proceed may store some of that energy as chemical energy in newly formed bonds.

EXAMPLE: The coals and woods. UNIT: Jouls. FORMULA: K.E. = \frac{1}{2} \times m \times v^2.

Magnetic energy: is an invisible force or field caused by the unique properties of certain materials. In most objects, electrons spin in different, random directions.

EXAMPLE: The Generator. FOMULA: E=1/2 LI2. UNIT: Teslas

Mechanical energy: is the energy that is possessed by an object due to its motion or due to its position

formula : mechanical energy = kinetic+ potential energy. UNIT: Newton Meter. EXAMPLE: Hammer, dart gun and wind mill.

Sound energy: is the movement of energy through a substance – such as air or water – in the form of waves

EXAMPLE: Balloon and popping horn

UNITS : 1 Joules per cubic meter(J/m3)

FORMULA:I = Δ p 2/ 2 ρ v w. Δ p Change in pressure, or amplitude p- density of the material the sound sound is travelling through vw - speed of observed sound.

Light energy: is a form of electromagnetic radiation. Light consists of photons, which are produced when an object's atoms heat up

EXAMPLE: Lightened candle, fire, flashlight and electric bulb

FORMULA: E = h f where: E = Energy of the photon (in Joules) h = Constant, actually known as Planck's constant, a really ugly number f = frequency of the light in units of per seconds (1/seconds)

UNIT: ELECTRON-VOLTS(eV)

Electrical energy: Electrical energy is a type of kinetic energy caused by moving electric charges.

UNIT: Watts and Kilowatts. FORMULA: Electrical energy=Power x Time. EXAMPLE: Washing machine, and dryer

Heat Energy: Heat is the form of energy that is transferred between systems or objects with different temperatures.

EXAMPLE: The sun. UNIT: calorie and kilo calorie. FORMULA: The equation for calculating heat energy is q=mCpΔT, where q is the heat variable, m is the mass of the object,Cp is the specific heat constant and ΔT is the temperature change

Formula P.E.=m×g×h

unit: joule