Thermal energy Flashcards
What is a system?
A system is a group of objects
What are the various ways in which energy can be stored in a system?
Thermal store: energy due to an objects temperature. Thermal stores increase when the object gets hotter and deacrese when it gets colder
Elastic store: energy due to an objects having a greater/shorter length than its natural length. Elastic stores increase if the object is streched or squashed and deacreses when it goes back to its natural form
Kinetic store: energy due to an objects mass and speed. Kinetic store increases if an objects speed increases and deacreases if an objects is slowed down
Gravitatinal store: energy due to an objects height above the earths surface. Gravitatinal stores increase if an object is lifted up and deacrease if it falls down
Chemical store: energy due to atoms combining in a chemical reaction
Electrostatic store: this is energy stored when similar charged objects are pushed together and when opposite charged objects are oulled appart
Nuclear store: this is energy assosiated witht eh nucleus of an atom. This changes if changes happen in the nucleus e.g in a fusion reaction
Magnetic store: this is the energy stored when like poles of a magnet are pushed closer together and unlike poles are pulled further appart
How can energy transfers take place?
Energy transfers happen because of forces doing work, a flow of an electrical current, heating, light, radiation, and sound waves
What is iternal energy?
Internal energy is the total kinetic and potential energy of all particles (atoms and molecues) that make up a system. The molecues kinetic store is related to how fast they are moving, and the molecues potential store is related to how far appart they are (in their bonds)
When an object is heated what ahppens to its internal energy?
The internal energy increases - either raises the temperature of the system or cuases change of state
How is the temperature of a gas related to the average kinetic energy of its molecues?
The molecues of gas are in a constant random motion. As the temperature of a gas increases the average kinetic energy of the molecus also increases.
What do we mean by the spersific heat capasity?
Its the energy (J) needed to increase the temperature of 1kg of a substance by 1*C
How can we measure the spersific heat capasity of a substance accuretly?
Sperfisic heat capasity = energy transfered (over)
mass x change in temperature
What is accurate data?
Accurate data is data which is close to the true value
What is precise data?
Repeated measurements how very little spread (aorund the same value)
What is reproducable data?
When the same data can be repeated (getting the same relsult with doing it again)
What is random uncertianty?
measurements to be spread around the mean value
What is systematic uncertaincy?
when a meausrement is always too high or too low
What is zero error?
When a measurment instrument reads a value when it should say zero
How do you reduce unwanted thermal energy transfers?
by lubrication (when parts move) and thermal insulation
