energy stores and transfers Flashcards
(18 cards)
Name the 8 types of energy stores.
Chemical, kinetic, gravitational potential, elastic potential, thermal, magnetic, electrostatic, nuclear.
Name the 4 ways energy can be transferred.
Mechanically, electrically, by heating, by radiation (light & sound).
What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transferred between stores.
If a ball is dropped, what energy transfers take place?
Gravitational potential energy → Kinetic energy → Thermal energy & sound when it hits the ground.
What is the formula for efficiency?
Efficiency = (useful energy output ÷ total energy input) × 100%
A light bulb has 100J of input energy but only 25J is useful light energy. What is its efficiency?
(25J ÷ 100J) × 100% = 25%
What does a Sankey diagram show?
It represents energy input, useful output, and wasted energy.
Why do machines waste energy?
Due to friction, air resistance, or heat loss.
What are the three ways thermal energy can be transferred?
Conduction, convection, and radiation.
Which method of heat transfer occurs in solids?
Conduction.
Which method of heat transfer occurs in liquids and gases?
Convection.
Which method of heat transfer does not need particles?
Radiation.
How does convection work?
Hot fluid rises, cools, then sinks, creating a convection current.
Give an example of convection in everyday life.
Hot air rising from a radiator.
Which surfaces are the best absorbers and emitters of heat radiation?
Black and matte surfaces
Which surfaces reflect heat radiation the best?
white and shiny surfaces
How can we reduce unwanted energy transfer?
Using insulation, lubrication, and reducing air resistance.
Why does insulation keep a house warm?
It reduces heat loss by conduction and convection.
