Energy (Seneca) Flashcards
What is a Kinetic store?
The energy stored by an object’s movement.
What is a Gravitational potential store?
The energy stored in objects raised above the Earth’s surface.
This energy exists because of the Earth’s gravitational field.
What is a Chemical store
The energy stored by the chemical bonds between atoms.
What is a Elastic potential store
The energy stored when an object is being stretched, compressed or squashed.
What is a Nuclear store
The energy stored in the nucleus of an atom.
The energy in the nuclear store can be released by radioactive decay.
What is a Internal (thermal) store?
The internal store of energy is the sum of the:
- kinetic energy stored in the particles of an object
- the chemical energy stored in chemical bonds between particles in the object.
Energy is added to your body’s 1. when you eat food.
Energy is stored there until you need it.
Your body then transfers it to your 2. when you need to keep warm, or to your 3. to move about.
- chemical store
- thermal store
- kinetic store
The amount of energy in an object’s internal energy is the …
sum (total) of the kinetic energy and potential energy stored in the object’s particles.
The temperature of a body (object) is a measure of the …
energy in the kinetic stores of its particles.
Increasing a body’s temperature increases the 1. , which means that 2.
- energy in the kinetic stores of the body’s particles
- the energy in the body’s internal store also increases.
kinetic energy=
1/2 ×mass(kg)×velocity(m/s)2
change in gravitational potential energy (J) =
mass(kg) ×gravitational field strength (N/kg) ×change in height (m)
The elastic potential energy (measured in joules) is equal to …
half the spring constant (in Newtons per metre) multiplied by the extension (in metres) squared.
v=
√(2E ÷ m)
Ee(j)=
0.5 x k (n/m)x e(m)2
E(m) =
√ ( 2Ee (j)/ k (n/m))
K (m) =
(2 x Ee (j)) / e (squared) (m)
Heating an object transfers energy to …
the object’s internal store of energy (the sum of the energy in the kinetic and chemical stores of its particles).
Energy transferred from one object to another via a force is an example of …
mechanical work
When an object falls from a building, the weight does …
mechanical work to transfer energy from the gravitational potential store to the kinetic store.
When you push a wheelchair, energy is transferred to the —– store of the wheelchair.
kinetic
———— can transfer energy from one object to another.
Light and other types of waves
An electrical current transfers ———from one object to another, such as a battery powering a torch.
energy
Methods of energy transfer:
- mechanical work
- electrical work
- heating
- waves
Which principle tells us that energy cannot be created or destroyed?
conservation of energy
Describe the energy transfer in a kettle.
Energy transfers from the electrical store of the mains power supply to the thermal store of the water.
Work is done …
by a force on an object.
Describe what happens to the energy when a object projected upwards
The object’s energy is initially in the kinetic store as it moves upwards.
The object’s energy is slowly transferred from the kinetic store to the gravitational potential store as it slows down and climbs higher.
Once the object reaches its highest point, all of its energy is in the gravitational potential store.
As the object falls again, energy transfers from the gravitational potential store to the kinetic store.
Describe what happens to the energy when an object accelerated by a constant force
Work is done by a force on an object.
This work is converted to the object’s kinetic store.
Describe what happens to the energy when a moving object hits an obstacle
The object’s energy is in the kinetic store at the start because it is moving.
When the object collides with the obstacle, energy is converted to:
The kinetic store of the obstacle (making it move).
The thermal store of the object and the obstacle (the particles in the object and the obstacle vibrate more).
Some energy remains in the object’s kinetic store as it moves away after the collision.
Describe what happens to the energy when water is brought to a boil in an electric kettle
Energy transfers from the electrical store of the mains power supply to the thermal store of the water.
Describe what happens to the energy when a vehicle slows down.
To begin with, the vehicle’s energy is in the kinetic store.
The brakes do work slowing the car down. During this process, energy is dissipated (lost) through heat and sound.
Heating an object increases the amount of energy in its ———- store.
internal
When an object is projected upwards, what store is its energy in at its highest point?
Gravitational potential
More work is done if you:
- push with the same force for a longer distance.
- push with a larger force for the same distance.
Work done(j) =
force (N) x distance (m)
work is the amount of …
energy transferred when a force moves something for example
Power (watts) =
Work done (j)/ time (s)
What is transferred to an object that has had work done on it?
Energy
work done=—————=change in energy
force×distance
work done=force×distance=
change in energy
The work done by a force is equal to the …
energy transferred to the object.
E=
VIt
The energy is equal to the potential difference multiplied by …
the current times by the time.
The energy is equal to the ————- multiplied by the current times by the ——-.
potential difference
time
Power is the …
rate of energy transfer (or work done).
The faster that energy is transferred (or work is done), the ———- the power.
higher
The power (measured in ———) is equal to the work done (in joules) divided by the time (in seconds).
watts
The power (measured in watts) is equal to the work done (in ———) divided by the time (in seconds).
joules
The power (measured in watts) is equal to the work done (in joules) divided by the time (in ———).
seconds
The more powerful a set of speakers is, the …
more sound energy will be produced.
The more powerful a lightbulb is, the …
more light energy will be produced.
The power (measured in watts) is equal to the work done …
(in joules) divided by the time taken (in seconds).
Car engines make a lot of noise and get hot when they are being used to move you about. Explain what happen to the useful and wasted energy.
- The useful energy store here is the kinetic store because you want the car to move you from one place to another.
- The heat and sound energy are wasted energy because they are of no use to you.
When wires are used in an electrical circuit, they heat up.
This is often not useful energy and so it is …
wasted (Dissipated)
In almost every energy transfer, friction creates heat energy and this energy is often…
wasted (Dissipated)
Efficiency =
(useful power output/total power input) x 100
The useful power output and total power input are measured in…
watts (W)
Efficiency =
(useful energy output/total energy input) x 100
The useful energy output and total energy input are measured in …
joules (J).
How is efficiency most often expressed?
As a percentage
To reduce the energy transfer, we might:
- Fit loft insulation (the roof).
- Use double glazing (windows).
- Use cavity wall insulation (walls).
- Fit carpets (floors).
