p1-p3 Energy P2 In Another Flashcards
(103 cards)
What is a system
A system is an object or group of objects
What happens when a system changes
The way energy is stored also changes
How to calculate kinetic energy
1/2x mass x speed^2
How to calculate elastic potential energy
1/2 x spring constant x extension^2
How to calculate gravitational potential energy
Height x gravitational field strength x mass
What is the specific heat capacity
The energy required to raise the temperature of 1kg of a substance by 1°C or 1K.
How to calculate thermal energy
Mass x specific heat capacity x temperature change
Define power
The rate at which energy is transferred or the rate at which work is done
Calculation for power
Energy transferred/time = work done/time
What is Conservation of energy
Energy cannot be created or lost but it is simply transferred or changed form
How to reduce energy wastw
Lubrication
• Oil in a motor
• Reduces friction
• So less energy is lost (as heat) through friction
Thermal Insulation
• Double Glazing
• Less useful thermal energy lost
What is efficiency
The efficiency is the ratio of the useful work done by a machine, engine, device, etc, to the energy supplied to it, often expressed as a percentage.
What happens when thermal conductivity is higher
The higher the thermal conductivity of a material, heat is allowed to travel through the material more easily, so the higher the rate of energy transfer by conduction across the material.
What is thermal conductivity in a building
Rate of cooling is low if walls are thick and thermal conductivity of the walls are low
• If the walls are thin metal sheets, heat would be lost very quickly.
Calculation for efficiency
Useful energy output/total energy input= useful energy output/total power input
How to increase the efficiency
Reducing waste output (lubrication, thermal insulation, etc.)
Recycling waste output (e.g. absorbing thermal waste and recycling as input energy)
Main energy uses
Transport
- Electricity generation
- Heating
Compare renewable energy resources to non renewable energy resources
Renewable energy is energy which can be replenished as it is used (e.g. wind will never stop).
- Non-renewable energy is used more for large-scale energy supplies due to the large energy output per kilogram of fuel - renewable resources cannot provide such a large amount of energy as easily.
Renewable energy has become more important due to the finite lifetime of fossil fuels, and so their development has become more important.
Renewable energy is not always the most reliable as:
• Solar doesn’t work in bad weather or night
• Wind is only intermittent.
Environmeral impact of fossil fuels
Involved in destroying landscapes,release harmful emissions such as co2 and methane
Environmental impacts of renewable energy resources
Release no emmisions,wind turbines can be considered an eyesore
Patterns and trends of energy use
During industrial revolution, fossil fuels became an important source of energy as it was easy to mine, and provided a lot of energy
- Only recently has renewable energy become more suitable - technology has had to develop a lot since industrial revolution to be able to harness such energy sources efficiently
- It is easier to use energy resources due to increasing pressure to cope with the public’s increasing power demands but harder to solve environmental issues due to political, social, ethical and economic considerations.
Define nuclear fuel
Elements that can be used to release massive amounts of
energy for generating electricity. Nuclear fuel is based on
uranium
What is a fossil fuel
A fuel, made from hydrocarbons, that formed millions of
years ago from the bodies of animals and plants. Fossil fuels
are a store of chemical potential energy.
What is geothermal energy
The energy resource found in Earth’s crust, due the thermal
energy of the rock of the crust is certain places on Earth.