Energy - forces doing work Flashcards
How can energy be transferred?
Mechanically
Electrically
Heating
Radiation
What happens to some of the energy when a system changes?
Dissipated
Stored in less useful ways
How can energy transfers be shown?
Sankey diagrams
What happens when there are energy transfers in a closed system?
There’s no net change to the total energy in that system
Ways that energy can be transferred:
Heating
Electrical equipment
Work done by forces
How can energy be transferred by heating?
Water heated on gas stove
When Pan of water is a (system), energy is transferred into the system by the heating
Heating the thermal energy stores in the pan and water
Increasing the temperature
How can energy be transferred by forces doing work?
Box (system) is lifted from the floor
Box lifted is work being done against gravity
Energy is transferred to the systems kinetic and GPE stores
How is energy transferred by electrical equipment?
E.g electric irons
Irons transfers energy electrically from the main power supply
To…
The thermal energy supplies in the metal plates
What happens when a force moves an object?
Work has been done on the object
Energy has been transferred
Equation for work done
Force x distance
Equation for change in gravitational potential energy (GPE)
Mass x gravitational field strength x change in height
What is energy transfers the same as?
Work done
Equation for kinetic energy:
1/2 x mass x velocity2
Equation for power:
Work done / time taken
Define power
The rate at which energy is transferred
