P1- Energy Flashcards
(67 cards)
What are the 11 stores of energy
Kinetic, Gravitational potential, thermal, chemical potential, light, sound, electrical, nuclear, elastic potential, electrostatic, magnetic
What is energy transfer
The same as work done
Description of kinetic energy
The energy store associated with moving objects
Description of gravitational potential energy
The energy an object acquires when it changes height (up)
Description of thermal energy
The energy a substance has due to its kinetic energy (movement of its particles, always transferred from hot to cold objects)
Description of chemical potential energy
A type of stored energy released by chemical reactions
Description of electrical energy
Caused by moving electrical charges, carried by wires
What can energy not be
Created or destroyed
Description of elastic potential
The store of energy that stretched or compressed objects experience
What can energy be
Stored, transferred or dissipated
What is joules
The amount of energy an object has
What does dissipated mean
The energy has been spread out to the point it is no longer usable
What is a system
An object or group of objects that interact.
When a system changes, what happens to the way energy is stored
The way energy is stored also changes
What is a closed system
Where no matter or energy can enter or leave
What are the 3 things the amount of energy transfers depends on
1) Temperature difference between the two objects (greater difference = greater rate of energy transfer)
2) The thermal conductivity of a material (higher = more energy transferred),
3) The thickness of the insulating material (thicker = less energy transferred)
What is useful energy transfer
When energy is transferred to the energy store a device is intended for
What is the energy store/ transfer of a javelin thrower
Chemical energy of athlete will decrease. Kinetic energy of javelin will increase and gravitational potential energy of javelin will also increase
What will energy always be wasted as
Heat and sound
What is efficiency
A measure of how good a device is at changing energy from one store to another
If a device is more efficient, will less or more energy be wasted
Less energy wasted
Efficiency equation
Useful energy output / total energy input
How are energy efficient light bulbs more efficient than normal light bulbs
More of the electrical energy that they are supplied with is converted into light energy and not heat
How is efficiency shown
As a percentage or decimal between 0 and 1
