Module 2 Chapter 1 Physical Quantities, Units and Measurements Flashcards
Unit for Acceleration
m s-2
metres per second squared
Unit for Density
kg m-3
kilograms per cubic metre
Unit for Electrical Charge
C
coulomb
Unit for Energy
J
joule
Unit for Force
N
newton
Unit for Momentum
kg m s-1
kilogram metres per second
Unit for Potential Difference
V
volt
Unit for Power
W
watt
Unit for Pressure
Pa
pascal
Unit for Velocity
m s-1
metres per second
Prefix: pico
p
10^-12
Prefix: nano
n
10^-9
Prefix: micro
µ
10^-6
Prefix: milli
m
10^-3
Prefix: centi
c
10^-2
Prefix: kilo
k
10^3
Prefix: mega
M
10^6
Prefix: giga
G
10^9
Prefix: tera
T
10^12
SI Unit for Mass
kg
Kilogram
SI Unit for Length
m
Metre
SI Unit for Time
s
Second
SI Unit for Temperature
K
Kelvin
SI Unit for Electrical Current
A
Ampere
SI Unit for Amount of Substance
mol
Mole
SI Unit for Luminous Intensity
cd
Candela
Examples of Random Errors
- Variable heating in circuits causing variations in the current being measured
- An unexpected large extension of a metal wire due to a fault in its structure
Examples of Systematic Errors
- Using a ruler with a fault in the measurements printed on it
- A parallax error caused by reading a scale at the wrong angle
What do random errors reduce?
Precision
What do systematic errors reduce?
Accuracy
Percentage Uncertainty Formula
(uncertainty/measured value) * 100
How can one measure uncertainty?
By using one of two methods:
- Calculating a % difference between your ‘best’ and ‘worst’ lines of best fit
- Combining your uncertainties for each of your measurements (either summing or multiplying them depending on how you use the values)
For y = ab, how would you find the uncertainty of y, given the uncertainties of a and b?
% uncertainty in y = % uncertainty in a + % uncertainty in b
For y = a/b, how would you find the uncertainty of y, given the uncertainties of a and b?
% uncertainty in y = % uncertainty in a + % uncertainty in b
For y = a^n, how would you find the uncertainty of y, given the uncertainty of a?
% uncertainty in y = (% uncertainty in a) * n
For y = a ± b, how would you find the uncertainty of y, given the uncertainties of a and b?
absolute uncertainty of y = absolute uncertainty of a + absolute uncertainty of b