4.1 Energy Flashcards
(22 cards)
What is a system in the context of energy changes?
A system is an object or group of objects. When the system changes the way energy is stored changes.
Give examples of systems where energy storage changes.
Examples include: an object projected upwards a moving object hitting an obstacle
What are the main ways energy is transferred in a system?
By heating, by work done by forces, and by work done when a current flows
What is the unit for kinetic energy, mass, and speed?
Joules (J), kilograms (kg), metres per second (m/s)
What assumption must be made for the elastic potential energy equation to be valid?
The limit of proportionality has not been exceeded.
What is specific heat capacity?
The amount of energy required to raise the temperature of 1 kg of a substance by 1°C.
What practical is used to determine specific heat capacity?
Investigating temperature change and linking work done or energy transfer to thermal energy increase in a substance.
What is the unit of power?
Watts (W) where 1 W=1 J/s
State the law of conservation of energy.
Energy can be transferred, stored, or dissipated, but cannot be created or destroyed.
What happens to energy in a closed system?
It is conserved; no net change to total energy.
What is meant by wasted energy?
Energy that is dissipated into less useful stores often as heat.
How can unwanted energy transfers be reduced?
Through lubrication and thermal insulation.
How does thermal conductivity affect energy transfer?
Higher thermal conductivity increases the rate of energy transfer through conduction.
How does wall thickness and conductivity affect building cooling rate?
Thicker walls and lower conductivity reduce the rate of energy loss.
In what forms can efficiency be expressed?
As a decimal or percentage.
What are some ways to increase efficiency?
Reducing friction, improving insulation, or using more efficient technologies.
List the main energy resources available on Earth.
Fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, tides, Sun, water waves.
What is a renewable energy resource?
A resource that is replenished as it is used.
What are the main uses of energy resources?
Transport, electricity generation, and heating.
Why are some energy resources more reliable than others?
They are available consistently regardless of weather or time of day (e.g. fossil fuels vs solar).
What are some environmental impacts of using energy resources?
Pollution, greenhouse gas emissions, habitat disruption, resource depletion.
Why can’t science always solve environmental energy issues?
Because of political, social, ethical or economic considerations.
