Energy

Energy Whenever an object is moved a distance by some force we say that work has been done on that object. The ability to do work is called energy – or, work is the transfer of energy, and energy is measured in joules just like work.

Energy Think of it this way – when you bounce a basketball, energy from your arm is transferred to the ball and it moves – work is done on the basketball – and the basketball gains energy If the transfer of energy is work, then power is the rate at which energy is transferred, or, Power = Energy transferred / Time

Kinetic Energy

Potential Energy

Major Forms of Energy MECHANICAL ENERGY – energy associated with the position and motion of an object Mechanical Energy = Potential Energy + Kinetic Energy A basketball has both potential (position above the ground) and kinetic energy (from the shooter’s arm)   A speeding car has only kinetic energy since it won’t be falling   A dinosaur fossil on a shelf has only potential energy

Thermal Energy THERMAL ENERGY – the total potential and kinetic energy of the particles in an object  Ice cream has low thermal energy  Hot burritos have higher thermal energy  Lava has more thermal energy than rocks

Electrical Energy ELECTRICAL ENERGY – the energy of electric charges. Depending on whether the charges are moving or stored, electrical energy can be kinetic or potential.   Lightning is electrical, kinetic energy   Batteries are electrical, potential energy

Chemical Energy CHEMICAL ENERGY – energy found in the bonds between atoms and molecules Molecules in foods like CARROTS or APPLES store chemical energy or chemical, potential energy During digestion, your body releases this energy

Nuclear Energy NUCLEAR ENERGY – the energy in the nucleus of atoms The nuclei of radioactive atoms store vast amounts of potential energy During nuclear fission, this energy is released

Electromagnetic Energy ELECTROMAGNETIC ENERGY – energy that travels in waves with both electrical and magnetic properties Microwaves and x-rays are types of electromagnetic energy Other forms include ultraviolet and infrared radiation and radio waves

HOW IS ENERGY TRANSFORMED FROM ONE FORM TO ANOTHER? Single Transformations – energy is transformed from one form to another Toaster – transforms electrical energy to heat energy Cell phone – transforms electrical energy to electromagnetic energy Human body – transforms chemical energy to mechanical energy

HOW IS ENERGY TRANSFORMED FROM ONE FORM TO ANOTHER? Multiple Transformations – energy is transformed to many different forms Striking a Match – mechanical energy to thermal energy to chemical energy to electromagnetic energy A car engine – electrical energy produces thermal energy which releaseschemical energy producing thermal energy leading to mechanical energy which in turn produces more electrical energy

Identify the Energy Transformation Which kind of energy do these devices use and produce? Steam iron Ceiling fan Digital clock Clothes dryer Electrical to Electromagnetic Electrical to Heat and Mechanical Electrical to Heat Electrical to Mechanical

Transformations between Potential and Kinetic Energy One of the most common energy transformations occurs between potential energy and kinetic energy. Roller coasters have high potential energy when they are on the hills. This potential energy is transformed into kinetic energy on the way down the hills. At the bottom of the hills, the roller coaster has high kinetic energy which is transformed back into potential energy as it climbs the next hill.

Pendulums Pendulums also display a continuous transformation between kinetic and potential energy.

Law of Conservation of Energy The Law of Conservation of Energy – when one form of energy is transformed into another, no energy is destroyed in the process – energy cannot be created or destroyed, only changed or transformed.

Fossil Fuels Fossil fuels – substances such as coal, petroleum, and natural gas that were formed from vast, ancient forests and animal remains. These fuels contain chemical potential energy. The source of this potential energy is the sun – the source of energy for most of earth’s processes. Plants, algae and some bacteria transform the sun’s energy and it is stored when they die.

Energy Transformations with Fossil Fuels The process of burning fossil fuels is called combustion – chemical energy is transformed into thermal energy. Thermal energy is then transformed into mechanical, electrical, and/or electromagnetic energy. Chemical energy thermal energy mechanical energy electrical energy electromagnetic energy