P8 Global Challenges Definitions:
Alternating voltage- a continually oscillating current flow, which results in the potential
difference across two points continually oscillating between a positive and negative value.
Artificial satellites- man-made satellites that have been sent into space for purposes such
as satellite imaging and communications.
Big Bang theory- the currently accepted model for the origin of the universe. It suggests
that the universe has expanded from an initially very small, hot and dense point.
Braking distance- the distance a vehicle travels under the braking force. This can be
affected by adverse road and weather conditions as well as the condition of the vehicle.
Circular orbits- the circular path that a satellite or planet may travel in. Since their
direction is continually changing, their velocity is always changing. Gravity provides
the required force for these orbits.
CMBR- cosmic microwave background radiation. This is electromagnetic radiation that is
found in small quantities all around us. It is suggested to have come from the high energy
radiation emitted by the Big Bang.
Constant temperature- bodies at a fixed temperature radiate the same average power
that they absorb.
Crumple zone- a vehicle safety feature that compresses during a collision. It increases the
time over which the momentum change occurs, and so reduces the force experienced
by the occupants.
Direct voltage- a one-directional current flow, which results in a fixed voltage polarity.
Earth wire- the green and yellow striped safety wire connected to metal casings, that
prevents an appliance from becoming live.
Human reaction time- the time it takes for our brain to respond to a stimulus. Typical
human reaction times are in the range of 0.2-0.9 seconds. A ruler-drop experiment could be
used to determine your reaction time.
Live wire- the brown coloured wire that carries the alternating current from the supply in a
mains power supply.
Main sequence star- the stable state of all stars. The gravitational forces pulling the star
together, and the pressure pushing outwards, are balanced.
Mains electricity- an a.c supply, which in the UK has a frequency of 50Hz a value of 230V.
Natural satellites- the moons that orbit planets.
Nebula- a cloud of dust and gas.
Neutral wire- the blue coloured wire that completes the circuit in a mains power supply.
Non-renewable energy resource- an energy resource that cannot be replenished whilst it
is being used. It is a finite resource.
Orbital radius- the radius of a body’s orbit. For a stable orbit, a change in its orbital
radius is required for the body to undergo a speed change.
P-waves- primary waves are a type of longitudinal seismic wave. They can travel
through all mediums and travel faster than S-waves.
Power cables- metal wires that are part of the National Grid. Electricity is transported along
them at very high voltages to reduce the energy loss and make the transportation more
efficient.
Protostar- the first stage all stars go through after forming from a nebula. In this stage the
star becomes hot enough for hydrogen nuclei to fuse.
Red giant star- when their hydrogen is used up and larger nuclei are produced by fusion,
Alternating voltage- a continually oscillating current flow, which results in the potential
difference across two points continually oscillating between a positive and negative value.
Artificial satellites- man-made satellites that have been sent into space for purposes such
as satellite imaging and communications.
Big Bang theory- the currently accepted model for the origin of the universe. It suggests
that the universe has expanded from an initially very small, hot and dense point.
Braking distance- the distance a vehicle travels under the braking force. This can be
affected by adverse road and weather conditions as well as the condition of the vehicle.
Circular orbits- the circular path that a satellite or planet may travel in. Since their
direction is continually changing, their velocity is always changing. Gravity provides
the required force for these orbits.
CMBR- cosmic microwave background radiation. This is electromagnetic radiation that is
found in small quantities all around us. It is suggested to have come from the high energy
radiation emitted by the Big Bang.
Constant temperature- bodies at a fixed temperature radiate the same average power
that they absorb.
Crumple zone- a vehicle safety feature that compresses during a collision. It increases the
time over which the momentum change occurs, and so reduces the force experienced
by the occupants.
Direct voltage- a one-directional current flow, which results in a fixed voltage polarity.
Earth wire- the green and yellow striped safety wire connected to metal casings, that
prevents an appliance from becoming live.
Human reaction time- the time it takes for our brain to respond to a stimulus. Typical
human reaction times are in the range of 0.2-0.9 seconds. A ruler-drop experiment could be
used to determine your reaction time.
Live wire- the brown coloured wire that carries the alternating current from the supply in a
mains power supply.
Main sequence star- the stable state of all stars. The gravitational forces pulling the star
together, and the pressure pushing outwards, are balanced.
Mains electricity- an a.c supply, which in the UK has a frequency of 50Hz a value of 230V.
Natural satellites- the moons that orbit planets.
Nebula- a cloud of dust and gas.
Neutral wire- the blue coloured wire that completes the circuit in a mains power supply.
Non-renewable energy resource- an energy resource that cannot be replenished whilst it
is being used. It is a finite resource.
Orbital radius- the radius of a body’s orbit. For a stable orbit, a change in its orbital
radius is required for the body to undergo a speed change.
P-waves- primary waves are a type of longitudinal seismic wave. They can travel
through all mediums and travel faster than S-waves.
Power cables- metal wires that are part of the National Grid. Electricity is transported along
them at very high voltages to reduce the energy loss and make the transportation more
efficient.
Protostar- the first stage all stars go through after forming from a nebula. In this stage the
star becomes hot enough for hydrogen nuclei to fuse.
Red giant star- when their hydrogen is used up and larger nuclei are produced by fusion,
