What is Energy?

Joke of the Day Where do you put dirty lab equipment?

Answer The zinc!

Energy – The ability to do work or to cause a change. Kinetic Energy The energy of motion. A moving object has the most kinetic energy at the point where it moves the fastest. Potential Energy Stored energy; the energy an object has due to its position, molecular arrangement, or chemical compostion.

Is it kinetic or potential energy Example Kinetic Potential Blood flowing through the body A car moving down the street An apple in a tree A bug crawling along a sidewalk A car at a stop sign An airplane sitting on a runway A guitar string vibrating Water in a waterfall

Is it kinetic or potential energy Example Kinetic Potential Blood flowing through the body X A car moving down the street An apple in a tree A bug crawling along a sidewalk A car at a stop sign An airplane sitting on a runway A guitar string vibrating Water in a waterfall x

Types of Potential Energy 1. Chemical Energy – Chemical energy is stored in the bonds of atoms and molecules. Examples: Biomass, Food, petroleum, natural gas, propane and coal. 2. Nuclear Energy – the energy stored in the nucleus of an atom. It is the energy that holds the nucleus together. Example: The radioactive decay of the nucleus of a uranium atom.

Types of Potential Energy (cont.) 3. Gravitational Energy – the energy of place or position. Example: Water that is held in a reservoir behind a hydropower dam has gravitational potential energy. 4. Stored Mechanical (elastic) energy – the energy stored in objects or substances by the application of force. Example: Compressed metal springs and stretched rubber bands.

Types of Kinetic Energy 1. Radiant (light) energy – is electromagnetic energy that travels in transverse waves. Examples: Visible light, x-rays, gamma rays, radio waves, and solar energy. 2. Thermal (heat) Energy – the internal energy in substances. It is the vibration and movement of atoms and molecules within substances. Example: Geothermal energy.

Types of Kinetic Energy (cont.) 3. Mechanical (motion) energy – The movement of objects or substances from one place to another. 4. Sound Energy – Sound is the movement of energy (vibrations) through objects or substances in longitudinal waves. 5. Electrical Energy – the movement of electrons. Example: Lightning and electricity

Identify the type and form of energy Example Form (s) Type (s) (Kinetic or potential) A running dog Thermal , Mechanical, Chemical KE A burning candle A book on a table A green plant Sunlight A battery A cup of coffee

Identify the type and form of energy Example Form (s) Type (s) A running dog Mechanical, Thermal, Chemical KE, PE A burning candle Thermal, Chemical, Light A book on a table Gravitational PE A green plant Chemical PE, KE Sunlight Radiant, Light, Thermal KE A battery Chemical, electrical A cup of coffee Thermal, chemical

Kinetic Energy Both Moving Energy Kinetic Energy increases as mass increases The amount of Kinetic energy is determined by mass and velocity. Thermal Mechanical Electricity Radiant/Light Sound Stored Energy due to an object’s position and Chemical composition Nuclear Chemical Elastic (Stored Mechanical) Gravitational Both have the ability to cause change. Kinetic Energy Potential Energy

Class Notes:Calculating Energy To calculate the kinetic energy of a moving object you must know the mass and velocity. To calculate you use the following formula: Kinetic energy (KE) = 1 mass x velocity2 2

What is the kinetic energy of a 5 kg object moving at 7 m/s? KE = ½ (mass) x (velocity)2 KE = ½ (5 kg) x (7 m/s)2 KE = 2.5kg x 49 m2/s2 KE = 122.5 kg●m2 is equal to Joules s2 KE = 122.5 Joules

What is the kinetic energy of a 10 kg object moving at 8 m/s? KE = ½ (mass) x (velocity)2 KE = ½ (10 kg) x (8m/s)2 KE = 5kg x 64 m2/s2 KE = 320 kg●m2 s2 KE = 320 Joules

Calculating Potential Energy To calculate the potential energy of an object you must know the mass, height, and gravitational velocity (g = 9.8m/s2). To calculate you use the following formula: GPE = mgh Gravitational Potential Energy = mass x gravitational velocity x height

What is the gravitational potential energy of a diver with a mass of 60 kg who is 10 m above the water? GPE = mass x gravitational velocity x height GPE = 60 kg x 9.8 m/s2 x 10 m GPE = 60 kg x 98 m2/s2 GPE = 5,880 Joules

What is the gravitational potential energy of a rock with a mass of 20 kg who is 5 m above the ground? GPE = mass x gravitational velocity x height GPE = 20 kg x 9.8 m/s2 x 5 m GPE = 20 kg x 49 m2/s2 GPE = 980 Joules

Energy Transformations Energy can be transformed from one form to another. Devices such as light bulbs, hair dryers, and automobile engines convert one form of energy into other forms. Mechanical energy = Kinetic Energy + Potential Energy

How many examples of energy transformations can you fill in the chart below? Chemical Electric Heat Light Mechanical Sound Battery Car Running Television Stove Tread Mill Radio Fire Sun, Lava, Stop Light Running Microwave Echo

The Law of Conservation of Energy According to the law of conservation of energy, energy cannot be created or destroyed (it can only be transformed from one form to another). Friction converts mechanical energy into thermal energy. Fission and fusion are nuclear reactions that convert a small amount of mass in a nucleus to an enormous amount of energy

How are work and energy created? When work is done, energy is transferred.

Classwork Complete NTG section 13.1 and 13.2