practical and investigative skills Flashcards
What are physical quantities?
Things you can measure - has to have a size and usually a unit
What are some examples of quantities that don’t have a unit?
Magnification and efficiency
How many base units are there?
7
What are derived units?
When a quantity doesn’t have its own unit, it is made from the base units
How are newtons expressed in base units?
kgms-2
How are pascals expressed in base units?
kgm-1s2
How are joules expressed in base units?
kgm2s-2
What is dimensional analysis?
Analysis using the fact that physical quantities equated with each other must be expressed in terms of the same base quantities (e.g. mass, length)
Prefix for 10^ -12?
pico (p)
Prefix for 10^ -9?
nano (n)
Prefix for 10^ -6?
micro (µ)
Prefix for 10^ -3?
milli (m)
Prefix for 10^ -2?
centi (c)
Prefix for 10^ 3?
kilo (k)
Prefix for 10^ 6?
mega (M)
Prefix for 10^ 9?
giga (G)
Prefix for 10^ 12?
tera (T)
What are the seven base quantities and their units?
- time - seconds, s
- length - metres, m
- mass - kilograms, kg
- temperature - kelvin, K
- electric current - ampere, A
- amount of substance - mole, mol
- luminous intensity - candela, cd
when you see these ke words what do you do?
1) state?
2) describe?
3) discuss?
4) explain?
1) state- give a definition, example or fact
2) describe- do not explain just describe what happens
3) discuss- more detailed- state, describe and explain what happens
4) explain- state and give reasons
what is accuracy?
accuracy is how close the answer is ti the true answer
what are systemic errors?
systemic errors cause each value t differ from the true value by the same amount each time. eg background radiation
what is precision?
precision is when the smaller the data spreads from the mean the more precise it is.
what are random errors?
random errors cause readings to be spread about a true value in an unpredictable way. they affect precision.
