Energy Transfers Flashcards
What is the equation for gravity potential energy?
Mass x Gravitational Field Strength x Height
What is the equation for kinetic energy?
1⁄2 x Mass x Velocity2
What is meant by the conservation of energy?
the total amount of energy in a closed system remains constant
energy cannot be made or destroyed but can change from one form to another
Describe the energy changes that occur in a filament light-bulb.
electrical energy is transferred into light and heat energy
light is a useful energy form, heat is waste energy
What is waste energy?
energy that is not used by the device for its desired purpose, or converted into the desired form.
state the equation for efficiency
useful energy transferred by device
————————-
total energy transferred by device
three methods of reducing heat loss
double glazing
loft and wall insulation
thicker walls
how can we reduce heat loss in general
lubrication
thermal insulation
low resistance wires
define thermal conductivity
how good a material is at conducting heat
define and explain how lubrication is used
applying a substance such as oil/grease to minimise friction, heat loss
reduces friction which reduces heat loss and reduces wear and tear
define and explain thermal insulation
applying a material that reduces the amount of heat that is transferred from the system to its surroundings.
it insulated hot locations and keeps them hot
explain how low resistance wires are used
means that less power is converted to heat then lost, more power gets the the intended destination
