Thermal Energy Flashcards
What is a system?
A system is an object or group of objects
What are the various ways in which energy can be stored in a system (8)
- Thermal store
- Elastic store
- Kinetic store
- Gravitational store
- Chemical store
- Electrostatic store.
- Nuclear store
- Magnetic store
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 internal energy?
Internal energy is the total kinetic and potential energy of all the particles (atoms and molecules) that make up a system. The molecules’ kinetic store is related to how fast they are moving, and the molecules’ potential store is related to how far apart they are (their bonds).
When an object is heated what happens to its internal energy?
When a substance is heated the energy transferred to it increases the internal energy of the system. This either raises the temperature of the system (increases the kinetic energy of the particles) or causes a change of state (increases the potential energy of the particles)
How is the temperature of a gas related to the average kinetic energy of its molecules?
The molecules of a gas are in constant random motion. As the temperature of a gas increases the average kinetic energy of the molecules also increases, this means the particles move around more quickly.
How do you calculate the amount of energy transferred to or released from an object when its temperature changes? [you do not need to learn this equation, just be able to use it]
Change in energy = mass × specific heat capacity x change in temperature
ΔE = mcΔϴ
Energy (Joules, J), Mass (kilograms, kg), Specific heat capacity (J/kg℃),Change in temp (℃ or Kelvin, K)
What do we mean by specific heat capacity?
The specific heat capacity of a substance is the energy (in J) needed to increase the temperature of 1 kg of a substance by 1 0C (or Kelvin can be used too)
How can we measure the specific heat capacity of a substance accurately?
The mass of the metal block is measured using a balance.
The immersion heater is connected to a power supply and transfers energy to the block, this energy is measured using a joulemeter.
The insulation reduces the amount of energy that is transferred to the surroundings, this reduces uncertainty in the value for the specific heat capacity.
The specific heat capacity is calculated by:
Specific heat capacity =energy transferred
mass x change in temperature
What is accurate data?
Accurate data is data which is close to the true value
What is precise data?
Precise data is data in which repeated measurements show very little spread about the mean value.
What is reproducible data?
If another person can get the same result with the same, or different method/equipment, then the data is reproducible
What is repeatable data?
If the same person can get the same result with the same equipment and method then the data is repeatable.
What is random uncertainty?
Random uncertainty causes measurements to be spread around a mean value. The effect of random uncertainty can be reduced by repeating and averaging data.
What is systematic uncertainty?
Systematic uncertainty occurs when measurement is always too high or too low for each repeat. Usually because of an error in the equipment e.g a badly calibrated thermometer.
