P1 - Energy Flashcards
What are the 8 Energy Stores?
- Thermal Energy
- Kinetic Energy
- Gravitational Potential Energy
- Elastic Potential Energy
- Chemical Energy
- Magnetic Energy
- Electrostatic Energy
- Nuclear Energy
How is energy transferred?
Energy is transferred mechanically (by a force doing work), electrically (work done my moving charges), by heating or by radiation.
What is a System?
A System is the single object or group of objects that you are interested in.
What happens when a system changes?
Energy is transferred into or away from the system.
What is a closed system?
A closed system are systems where neither matter nor energy can leave.
The net change in the total energy is always zero.
What is a Kinetic Energy Store? How do you find the amount of Kinetic Energy?
A Kinetic Energy Store is the movement of an object.
To find Kinetic Energy (J), do Ek=1/2mv^2
Kinetic Energy = 1/2 mass x speed ^2
What is a Gravitational Potential Energy Store? How do you find the amount of energy in this store?
Gravitational Potential Energy is caused when an object is lifted.
To find the amount of energy in this store, do Ep = mgh
(g.p.e = mass x Gravitational field strength x height)
What is an Elastic Potential Energy Store? How do you find the amount of energy in the store?
Elastic Potential Energy is made when an object is stretched or squashed.
Elastic Potential Energy can be found by Ee = 1/2ke^2
(Elastic Potential Energy = 1/2 spring constant x extension^2)
What is a specific heat capacity?
The amount of energy that is needed to raise the temperature of 1kg is a substance by 1 degree.
How do you find the change in Thermal Energy?
ΔE= mcΔθ
Change in Thermal Energy = mass x Specific heat capacity x Temperature Change
What is the ‘Conservation of Energy Principle’?
The Conservation of Energy Principle is that Energy can be transferred usefully, stored or dissipated, but can NEVER be created or destroyed.
How to find the Power of an energy transfer? (E.g. the rate of doing work)
P = E / t
Power w = Energy transferred / Time s
How can you reduce the amount of Unwanted Energy Transfers?
Through lubrication and through thermal insulation.
Name the two ways of calculating Efficiency.
1) Efficiency = Useful Output Energy Transfer / Total Input Energy Transfer
2) Efficiency = Useful Power Output / Total Power Input
Is Useful Energy Input equal to Total Energy Output?
NO!!!