physics chapter 1 measurement Flashcards
what are the 7 base units
luminous intensity(cd)
temperature (K)
length (m)
mass(kg)
time(s)
amount of substance (mol)
current (A)
what is a homogenous equation
it is an equation where every term on both sides of the equation have the same SI base units
how to do estimation?
use common formulas
make a problem simple
comparing with known values in daily life
give to 1s.f.
how to resolve vectors
split the vectors into 2 perpendicular components
- one horizontal and one vertical
precision refers to?
the degree of agreement of repeated measurements of the same quantity
what does accuracy refer to ?
refers to the degree of agreement between the result of measurements and the true value of the quantity
how to determine precision
look at the spread
wider spreader less precise
how to determine accuracy?
compare the average of the readings and compare it with the true value
closer average means higher true value
how to find absolute uncertainty of a measured quantity
half of the smallest division express using the same d.p
how to find absolute uncertainty of derived quantities
- make the required quantity a subject of the equation
- Decide whether to use rule 1 and Rule 2 or both
- calculate value of the subject
- then calculate uncertainty
express 1s.f./2s.f.
how to resolve the force of weight on a slope
- friction (along the slope)
- normal reaction force (contact force with slope)
what is rule 1 and when to use it
sum uncertainties together(multiply any constant coefficients) to form a value
for adding and subtracting
express to 1s.f. for precision
2s.f. for actual value
when to use rule 2 and when to use it
for power and multiplication and division
express as sum of fractional uncertainties
any powers must be brought down and modulus it and times to that quantities fractional uncertainties
express to 1s.f. for precision
2s.f. for actual value
how to find relative velocity ? for 1 direction
- identify the positive direction
- A relative to B
- A - B
how to find Relative velocity of 2D
draw vector diagram of the 2 velocity and take the relative velocity as the answer
rule 3 when is it used?
1/2(max quantity - min quantity)
for complex math like lg
