Scope of the presentation Scope of this presentation is to learn below engineering concept : Mass and Energy

Introduction:Mass and Energy Before learning Energy conservation law, let us understand … We are part of universe. Our earth is in solar-system. Our solar system is in a galaxy. There are many galaxies in the universe. All that exists is in the universe. The universe is endless. The universe can not be created or destroyed. The universe is made up of matter and energy

Galaxy Solar System Universe Earth We all are part of universe. The universe is made up of matter and energy

Introduction:Mass and Energy

Matter Matter is anything that occupies space and has mass. Some matter is easy to see (water, wood), others are difficult (air, dust). The most basic building block of matter is the atom.

Matter classification Matter can be classified by its state. Solid: closely-packed particles with fixed locations Liquid: closely-packed particles, but free to move around Gas: great distances between particles with free movement

Can be mixed or dissolved with other matter Soil + water  mud (mixture) Sugar + water  syrup (solution) Can change crystalline form snowflake vs. ice solid ice on lake vs. “honeycomb” ice limestone vs. mother of pearl Matter

Energy is the ability to do work. Work is the energy transferred to or from a system by a force that acts on it. Energy

Symbol: E Scalar Units: J, Joule cal, calorie kcal, kilocalorie (Cal) Energy

Law of Conservation of Matter  MASS before = MASS after In all these changes, no loss or gain of matter  There is no AWAY. What we “throw away” is still here somewhere.  { Exception: Nuclear fission or fusion—mass converted to energy in nuclear power, atomic bomb, core of sun. }

The Law of Conservation of Energy Energy can change from one form to another, but the total amount of energy never changes.

Law of Conservation of Energy What you put in is what you get out Total energy is conserved

Law of Conservation of Energy Einstein showed relation between mass and energy. He showed mass and energy can be converted into each other. But it is not possible to convert matter into energy in normal conditions. It can be done in nuclear reactors Law is expressed by the formulae : E = m * c 2

n other words: E = energy (measured in joules, J)joules m = mass (measured in kilograms, kg)kilograms c = the speed of light (measured in metres per second, ms -1 )metressecond

How much energy is stored in 1 Kg of mass ? 1. E = m * c 2 ( m= mass in Kg, C = speed of light 3 * 10 8 in m/s 2 ) 2. Find the values: E = 1 kg * ( 3 * 10 8 ) 2 = 1 * 9 * Joules This means 1 kg of mass can release 9 * Joules of energy.

Confused with the numbers??.Let’s calculate, What such amount of energy means? - First convert it into calories. 4.2 Joules = 1 cal -Therefore 9 * Joules = (9 / 4.2) * calories = approx. 2 * calories Therefore 1 Kg of mass contains approx. 2 * calories Generally 1 gm of oil contains calories. 1 kg of oil contains = * 1000 = = 10 7 calories Therefore to get 2 * calories energy we will need 20 lacks tons of oil. In other word, 1Kg of mass contains 20 lacks tons of oil.

Mass and Energy balance Let’s study following examples : Example 1 : If 100gm wood is burned in air then … - It produces 2gm of ash. - Where did the balance of 98 gm go ? You may find some gas and vapor goes into air. In the above example, we found gm of Carbon dioxide (CO 2 ) and 58.9gm of water vapor gets generated in the process. The material balance is written as follows : gm wood  2 gm (ash) gm (CO 2 ) gm (water) i.e total 204.5g. 100 gm wood  gm of above materials This means 104.5g other material (Oxygen -O2) gets added in the burning process from outside.