P1-3 Flashcards
(16 cards)
Define a system
A system is an object or group of objects
What is the formula for Kinetic energy
Ek = 1/2 mv^2 ( 1/2 x mass (kg) x speed (m/s)^2 )
What is the formula for elastic potential energy
Ee = 1/2 ke^2 ( 1/2 x spring constant (N/m) x extension (m)^2 )
What is the formula for gravitational potential energy
Ep = mgh ( mass x gravitational field strength (9.8ms^-2) x height (m) )
What is the formula for specific heat capacity (The energy required to raise the temperature of 1kg of a substance by 1°C or 1K)
𝐸 = mc∆𝑇 (energy = mass × specific heat capacity × temperature change)
Define power
The rate at which energy is transferred or the rate at which work is done
What is the formula for power
P = E/t = W/t ( power = energy transferred/time = work done/time)
What are ways of reducing energy waste
Lubrication (oil in a motor, reduces friction, less energy is lost as heat)
Thermal insulation (double glazing, less useful thermal energy lost)
Define efficiency
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 is the formula for efficiency
Efficiency = useful energy output/total energy input = useful power output/total power input
How can efficiency be increased
- Reducing waste output
- Recycling waste output
What are the main non-renewable energy sources
Fossil fuels (coal, oil, gas)
Nuclear fuel
What are the main renewable energy sources
Biofuel, wind, hydro-electricity, geothermal, tidal, solar, water waves
What are the main energy uses
Transport, electricity generation, heating
Environmental impacts of the extraction of energy
Fossil fuels involve destroying landscapes, wind turbines can be considered an eyesore
Environmental impacts of the use of energy sources
Fossil fuels release harmful emissions, solar, wind directly create electricity with no emissions
