Energy Flashcards
What are the eight energy stores?
Kinetic, gravitational potential, elastic potential, thermal, chemical, nuclear, electrostatic and magnetic.
Where does waste energy end up?
Lost to the surroundings, often as heat or sound.
What is meant by a system in energy changes?
An object or a group of objects.
What is kinetic energy?
The energy store of moving objects.
Where does all energy ultimately end up?
It will dissipate into the surroundings, increasing the internal energy of the surroundings.
What is power?
The rate at which energy is transferred (J/s = W).
What is the conservation of energy?
Energy can not be created or destroyed, only transferred from one energy store to another.
What form is energy most commonly wasted as?
Heat/thermal energy.
How can waste heat be reduced?
Using lubrication or thermal insulation to contain heat.
How is energy transferred in a solid?
Conduction.
What is conduction?
The transfer of energy, such as heat or an electric charge, through a substance.
What is renewable energy?
An energy resource that can be replenished as it is used.
What are four non-renewable energy resources?
Coal, oil, gas and nuclear.
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a substance by 1°C.
Why will theoretical velocity not normally be reached?
Due to friction and resistance.
What happens to energy when it is transferred in a closed system?
There is no net change in the total energy, it is conserved.
What energy change occurs when a moving object hits an obstacle?
The object’s kinetic energy is transferred to the obstacle, possibly as sound, heat and/or permanent deformation of the obstacle.
What energy change occurs when an object accelerates by a constant force?
The object’s kinetic energy increases as work is being done (energy is being transferred as a force is acting over a displacement), and the object accelerates at a constant rate.
What energy change occurs when a vehicle slows down?
The vehicle’s kinetic energy decreases. Energy is being transferred into a store of thermal/heat/internal energy, possibly in brakes, surfaces, and air. The vehicle decelerates.
What energy change occurs when water boils in an electric kettle?
The water’s store of heat/thermal/internal energy increases and energy is transferred from electrical energy.
How can materials be used for insulation?
When thermal conductivity of a material is low, the rate of thermal energy transfer by conduction across material is low, it insulates. The thicker the wall, the lower the rate of cooling.
How can you improve energy efficiency?
Reducing unwanted energy trasnfer/store.
What factors affect the thermal conductivity of a building?
Temperature, moisture content, and density.
What are the use, reliability and environmental impacts of renewable and non-renewable energy sources?
Renewable energy sources like solar and wind are sustainable and reduce emissions, but their output can be unreliable due to weather dependence. Non-renewable sources, such as fossil fuels, are reliable but cause significant environmental harm through pollution and climate change.
