Energy Flashcards
The Law of conservation of energy
Energy can not be created or destroyed, but it can be transformed from one energy store into another.
Stores of energy
chemical, kinetic, gravitational, elastic, thermal (heat), magnetic, electrostatic, nuclear.
Energy transfers
Mechanical – A car applies a force and transfers chemical energy into Kinetic Energy
Electrical – A battery is a store of chemical energy which is transferred into heat and light in a bulb
Heating – Thermal energy is transferred from hot objects to cold objects while cooking
Radiation – The sun transfers energy from itself to the Earth by light waves
what happens to energy that is ‘lost’ during heat transfer?
it is transfered in to heat and sound, which are called less useful forms of energy
Total Energy Input = Useful Energy Output + Less Useful Energy
Efficiency always has a value less than 1. What does this tell us?
It tells us that the useful output energy is always less that the input energy. There is always some energy lost during energy transfer
SANKEY DIAGRAM
-The width of the arrows is in proportion to the amount of energy involved.
-The length of the arrow does not matter.
-The arrow for the less useful energy usually goes down
Conduction def, example and best insulator to prevent this
heat energy is transmitted from one object to another by direct contact and by which heat is transferred from the hotter end to the colder end of an object. Conduction occurs more readily in solids and liquids, where the particles are closer together than in gases, where particles are further apart. This heat transfer is caused by vibrations and collisions between neighboring molecules. When there is energy particles vibrate, transferring thermal energy.
Example: A common example of conduction is the process of heating a pan on a stove.
Best insulator: The best insulator for conduction would be a vacuum as there would be no way to transfer the heat, because there is no particles to transfer the vibration and energy.
Convection def and example
Convection is the transfer of heat through the movement of a fluid, such as a gas or liquid. It happens when there are temp differences in fluids. When fluid is heated the particles expand become less dense and therefore rise and take the place of the cooler, denser fluid sinks that begin to sink. This movement is known as a convection current, which transfers heat from one location to another.
Example: Convection can accure when hot air rises above a hot pan.
Radiation def, example and best insulator to prevent this
Radiation refers to the emission of energy through space and vacuum by electromagnetic waves. Radiation transfers thermal energy by electromagnetic waves, such as infrared radiation, visible light, and ultraviolet radiation.
Example: Unlike conduction and convection radiation can occur through empty space, making it the best way of heat transfer between the sun and the Earth.
Describe how double glazing and loft insulation are both effective ways to keep a house warm
They both reduce heat loss through windows and roofs.
Double glazing is a type of window that consists of 2 class panes which is separated by a gap of air or vacuume. This gap acts like a insulator to reduce the amount of heat that is lost through the window and prevents cold air from outside from entering the house and heat from being lost. It also reduces conduction because it is not a good conductor.
Loft insulation involves adding a layer of insulating material to the roof of a house, which helps to prevent heat from escaping through the roof through convection. Heat rises, so without insulation, heat can be lost. Insulated roofs reduce heat lost of the air that rises as the fibers trap the air meaning it can’t move, therefore convection can’t occure.
Describe and explain how a Mylar blanket and a thick woolly jumper can be used by a person to keep warm
A Mylar blanket is made of a thin and lightweight sheet of Mylar coated with a thin layer of aluminum. The Mylar layer helps to reflect the person’s body heat back to them and prevent it from escaping into the surrounding environment.The Mylar blanket are shinny, meaning we trap the heat inside and reduce heat radiation.
A thick woolly jumper is made out of wool fibers that trap a layer of air between the fabric and the skin. Air is a poor conductor of heat, so the trapped layer of air acts as an insulating layer keeping body warm. This process is known as conduction, and it helps to slow down the transfer of heat from the body to the surrounding environment.
Work
Whenever an energy transfer takes place Work is done.
Power
Power is the rate of doing work or how much energy is transferred in a particular length of time.
Weight
Weight is the force of gravity which pulls an object down to the ground.
units of work
joules (J)
