P1 - Energy Flashcards
What are the 5 main stores of energy?
1 - Chemical potential
2 -Elastic potential
3 - Gravitational potential
4 - Kinetic
5 - Thermal (heat)
What are the 5 ways that the energy is transferred?
1 - Forces
2 - Sound
3 - Heating
4 - Electric current
5 - Electromagnetic waves
What is ‘work done’ and what is the equation for it?
Work done is energy transferred
Work done(J) = force(N) × distance(m)
What is the equation for kinetic energy Ek?
Ek = ½mv²
Ek = 0.5 × mass × (speed)²
What is the equation gravitational potential energy Ep?
Ep = m×g×h
Ep = weight × height
What do k and e stand for in the equation for elastic potential energy
Ee = ½ke²?
k - the spring constant
e - the extension
What is the equation for efficiency?
Efficiency = useful energy transferred/total energy transferred
What happens to energy that is not usefully transferred?
It is lost to the thermal store od the surroundings
- Usually transferred away by heating or sound
What is the equation for power and what does power mean?
Power = Energy transferred ÷ time
Power is the rate of energy transfer
- Shows how much energy is used every second
Measured in watts (W)
What are the energy transfers that take place when an object falls through the air?
Gravitational potential energy turns into kinetic energy as an object falls through the air
What is the unit of energy?
The Joule (J)
What is the definition of ‘specific heat capacity’?
It is the energy needed to raise the temperature of 1kg of a substance by 1°C
What do the symbols c and Δθ mean in the equation ΔE = mc Δθ ?
c is the specific heat capacity
Δθ is the change in temperature
What 3 factors does the energy transfer per second through a material depend on?
1 - Thermal conductivity of material
2 - Thickness of the material
3 - Temperature difference between the 2 sides of the material
Every time energy is transferred from one store to another only some of the energy is transferred usefully.
What happens to the rest?
Some of the energy is dissipated (spreads out) and is stored in less useful ways
E.g. Heating up the surroundings
Why is the kinetic energy of an object as it hits the floor not the same as its gravitational potential energy before it is dropped?
As the object falls some of the energy is dissipated (spreads out) to the surroundings.
This heats up the air a little bit
How does the insulation in a coat keep you warm?
The insulation in a coat traps air.
Air has a low thermal conductivity so it takes more time for the heat energy to pass through it
What is a renewable energy resource?
Energy from natural sources that is always being replenished so it never runs out
Give 4 examples of non-renewable energy resources.
1 - Coal
2 - Oil
3 - Natural gas
4 - Nuclear
What are the 3 things that energy resources provide energy for?
- Heating
- Transport
- Generating electricity
What are the 5 factors that are taken into consideration when making decisions about which energy resources to use?
1 - Environmental
2 - Political
3 - Social
4 - Ethical
5 - Economic
List 7 renewable energy resources.
1 - Solar
2 - Wind
3 - Wave
4 - Tidal
5 - Hydroelectic
6 - Geothermal
7 - Biofuels
What are the environmental consequences of using fossil fuels?
Burning fossil fuels releases carbon dioxide that contributes to the greenhouse effect.
This leads to global warming.
Does nuclear power contribute to the greenhouse effect?
No.
Nuclear power does not emit carbon dioxide.
What will happen to the percentage of electricity generated from renewable resources over the next 20 years?
It will increase because fossil fuels are running out
What are the disadvantages of using solar and wind power?
Sola and wind power are unreliable.
They don’t produce electricity all the time.
Why can’t everyone use hydroelectric power?
It requires water sources that are in mountainous areas.
Not everywhere has mountains and water.
