WEEK 1 Flashcards
To maintain precision while solving any mathematical equation involving
numbers…
calculations and answers should always be reported in the same number of significant figures as that of the input variables provided
sig fig rules!
- All non-zero digits are significant
- Zeros appearing between any two non-zero digits are significant
- Leading zeros are not significant
- Trailing zeros in a number containing decimal point are significant
what is a unit?
provides measure to the numerical quantity associated with it
what are the fundamental units for distance and time respectively
metres (m) and seconds (s)
what are fundamental units?
units for physical quantities from which all other units can be generated
SI system fundamental units
kilogram (kg), metre (m), candela (cd), second (s), ampere (A), kelvin (K) and mole (mol)
Newton (N)
unit for force is composed of combination of fundamental units : kg m s-2
force (N) = mass (kg) x acceleration(ms^-2)
Joules (J)
unit for energy is composed of combination of fundamental units : kg m2 s-2
energy (J) = force (kg ms^-2) x distance (m)
Nucleogenesis
formation of new nuclei from existing nucleons
Nuclides
an atom with a particular mass number and atomic number
Isotope
nuclide with the same atomic number but a different mass number
exothermic
releases energy into surroundings as heat and radiation
every atom is generated…
from the simplest nuclide hydrogen by nuclear reactions
hydrogen burning
The star continues to burn H until it exhaust all H atoms, then begins to burn He to for increasingly larger atoms
New element-forming reactions are exothermic until iron
All elements up to iron are produced in stars
When a star has only iron to burn, it consumes energy and implodes, forming a supernova.
The decay constant (k)
is characteristic of the particular radioactive nuclide, and does not depend on the amount of sample.