P1 - Energy Flashcards
What are the energy stores ?
Kinetic, thermal, chemical, gravitational potential, elastic potential, electrostatic, magnetic and nuclear.
How can energy be transferred ?
Mechanically, electrically, by heating and by radiation.
How is energy transferred mechanically ?
When a force does work on an object, like a force pushing an object along the floor.
How is energy transferred electrically ?
When a moving charge does work, like when a current flows through a light bulb.
How is energy transferred by heating ?
When energy is transferred from a hotter to a colder object.
How is energy transferred by radiation ?
When energy is transferred by e.g. sound or light, when energy from the sun travels to Earth by light.
What is a system ?
The single object or group of objects you’re interested in ?
What is the conservation of energy principle ?
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
What is the formula for working out the energy in an objects kinetic energy store ?
Kinetic energy(J) = 0.5 × mass(kg) × (speed)^2 (m/s)^2
Ek = 0.5 × m × V^2
How can you find the energy in an objects g.p.e store ?
g.p.e(J) = mass(kg) × grav. field strength(N/kg) × height(m)
Ep = m × g × h
What does the conservation of energy principle dictate about the energy transfer between two stores ?
Energy lost form first store = energy gained in second store
How can you find the energy in an objects e.p.e store ?
e.p.e(J) = 0.5 × spring constant(N/m) × (extension)^2 (m)^2
Ee = 0.5 × k × e^2
What is specific heat capacity ?
The amount of energy needed to raise the temperature of 1kg of a substance by 1°C.
How can you work out the change in thermal energy of a substance ?
Change in thermal energy (J) = mass(kg) × specific heat capacity(J/kg°C) × temperature change(°C)
ΔE = m × c × ΔΘ
What is the conservation of energy principle ?
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
