Unit 2 - Definitions Flashcards
Protostar
A collection of dust and gas before nuclear fusion takes place
Conservation of Momentum
The total momentum before an event (collision/explosion) equals the total momentum afterwards, assuming no external forces act
Isotope
An atom with the same number of protons but a different number of neutrons
Nuclear fission
The splitting of a large nucleus to form two smaller ones, releasing LOTS of energy
Current
The flow of charge/electrons
Alternating current (AC)
Current which constantly changes direction
Half life
The time taken for the number of radioactive nuclei in a sample to decay to half the initial value
Thinking distance
The distance travelled between the driver seeing the hazard and pressing the brake
Nuclear fusion
The joining of two smaller nuclei to form a larger nuclei
Potential difference
The energy transferred per unit charge
Stopping distance
The braking distance + the thinking distance
Resultant force
The overall force acting on an object
Direct current (DC)
Charge/electrons flowing in one direction
Velocity
The speed of an object AND the direction it is moving in
