Energy and Matter All physical phenomena are governed by the laws of conservation of energy and matter

Energy is classified into three main forms Radiant Kinetic & Potential

This is energy from the Sun which is the result of nuclear fusion Radiant Energy This is energy from the Sun which is the result of nuclear fusion

Kinetic Energy This is the energy carried by objects in motion, like a locomotive. Kinetic Energy includes: 1. Mechanical energy carried by the moving parts of a machine 2. Thermal Energy of the random internal motion of particles in all substances

Calculate the KE of a 70kg man walking at 2.5m/s. m=mass v=velocity KE =1/2 mv2 Calculate the KE of a 70kg man walking at 2.5m/s. m=mass v=velocity

KE= ½ mv2 KE= ½x 70x(2.5)2 KE = ½ x 70x 6.25 KE=218.75 Joules m = 70kg v = 2.5 m/s KE = ? KE= ½ mv2 KE= ½x 70x(2.5)2 KE = ½ x 70x 6.25 KE=218.75 Joules

Potential Energy This is the energy possessed by objects because of the position or the arrangement of their particles In essence it is stored energy.

Gravitational Potential Energy The kind of energy carried by water before it falls through the spillway of a hydroelectric dam is called gravitational potential energy. Gravity is responsible for converting the potential energy of the water into kinetic energy , which is then able to do work

PE= m g h M=mass g=gravity (9.8m/s2) h=height What is the gravitational potential energy of a 2 kg ball at rest on a window sill, 40m up from the pavement?

PE=m g h m=2kg h= 40m g=9.8m/s2 PE = 2kg x 40m x 9 .8m/s2 PE = 784 Joules

Other forms of Potential Energy Electrical Energy is the energy that exists when objects with different electrical charges are separated. Batteries operate on this principle

Chemical Energy is the energy which exists in some substances because of the arrangement of their particles. Fuels and food contain Chemical Potential Energy

Measuring energy The common unit of energy is the calorie (cal) 1 calorie is the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius

The SI Unit of energy is the Joule (J) Joule in the long form is kg.m2/s2 4.184J = 1 cal 4.184 KJoule = 1Kcal or 1Cal How many kilojoules are there in an average size chocolate bar that has 200 Cal?

Energy stored in food is often given a unit that is related to the calorie. The Calorie (Cal) is 1000cal or 1 kilocalorie.

1cal =4.184 joules chocolate bar=200 Cal 200Cal x 4.184 KJ/Cal= Energy in one chocolate bar= 836.8KJ

Law of Conservation of Energy The law of conservation of energy states that energy can neither be created nor destroyed, it simply changes from one form to another

The energy crisis Q.If energy is neither created nor destroyed, then how could we run out?!

A. Our society relies on coal, natural gas & petroleum (crude oil) for about 90% of its energy needs.

Why is Coal and Petroleum so valuable? They are simple to get and use –we dig them or pump them and burn them! Burning releases their chemical energy The energy for these sources can be obtained from wind and solar, but its less convenient and more expensive.

Other non-fuel uses for petroleum include: Plastics Pharmaceuticals Ethanol Synthetic fibers PVA glue

Alternative Energy Sources More research and development will be needed to decrease out need for the energy we derive from fossil fuels. Conservation and reduction of individual use can contribute to the availability of fossil fuels into the future while alternatives are perfected.

Measure of the average KE of the particles in a sample. 2-2 Temperature Measure of the average KE of the particles in a sample. Can be measured directly.

Thermometer The modern thermometer used in our class is filled with colored alcohol. As the bulb is heated or cooled the liquid with expand or contract.

The Celsius Temperature Scale The freezing point of pure water at sea level is 0º C. The boiling point of pure water at sea level is 100º C.

Kelvin Temperature Scale SI Unit for temperature is Kelvin (K). The degree unit is not used in Kelvin (K),

The Difference between Kelvin and Celsius The main difference is the location of the zero point. The zero point for kelvin is called absolute zero. Absolute zero is equal to -273º C. Absolute zero is the point at which the motion of particles of matter has completely stopped.

Converting Kelvin and Celsius ºC = K – 273 K = ºC + 273 For example, the boiling point of water is 100 ºC is 373 K. K = 100 ºC + 273 K = 373 K

Convert 50. K to the Celsius scale ºC = K – 273 ºC = 50. K – 273 ºC = -223 ºC

Converting Fahrenheit to Celsius ºC = (ºF – 32) x 5/9 Convert 67F to C ºC = (67º – 32) x 5/9 = 19.4 ºC

Converting Celsius to Fahrenheit ºF = (9/5 x ºC) + 32 Convert -14 ºC to ºF ºF = (9/5 x -14º) + 32 = 6.8ºF