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Chapter 1, Instrument - Coggle Diagram
Chapter 1
Physical quantities
A quantity that can be measured
Consists of a numerical magnitude and a unit
Base quantities
Time
Second
s
Electric current
Amphere
A
Mass
Killogram
kg
Thermodynamic Temperature
kelvin
K
Length
Metre
m
Amount of substance
mole
mol
Candela
Derived quantities
Obtained through equations
Speed
Distance / Time = m/s
Density
Mass / Volume = kg/m^3
Prefixes for SI units
Represents physical quantities that are very big or very small
Multiples
10^12 : tera- : T
10^9 : giga- : G
10^6 : mega- : M
10^3 : kilo- : k
Sub-multiples
10^-1 : deci- : d
10^-2 : centi- : c
10^-3 : mili : m
10^-6 : micro- : μ
10^-9 : nano- : n
Measuring physical quantities
Precision of an instrument
Time measurement
T = Period [s]
Pendulum
Period = 2π
√
length/gravitational field strength
Stopwatch
Mass
Symbol: m
SI unit: kilogram
Symbol for unit of mass: kg
Scalars and Vectors
Scalar quantities
Physical quantities that have only magnitude
Examples
Mass
Energy
Speed
The distance moved per unit time
Time
Distance
Total length by a moving object regardless of the direction of motion
Vector quantities
Physical quantities that have both magnitude and direction
Examples
Acceleration
Force
Velocity
The rate of change of displacement
Weight
Displacement
Distance measured in a straight line in a specific direction
Adding two vectors using the Graphical Method
Vector Diagram
Displacement-time graph
Curve
Gentle to steep:
Gradient increases
= velocity increases
Acceleration present
Steep to gentle:
Gradient decreases
= velocity decreases
Deceleration present
Steady slope
Gradient increases/decreases
= velocity increases/decreases
Acceleration/deceleration absent
Steady straight
Gradient = 0
hence velocity = 0
No movement = no acceleration
Instrument
Measuring tape
Zero to several metres
0.1cm or 1mm
A person's waist
Metre rule
Zero to one metre
0.1cm or 1mm
Height of table
Digital callipers
Zero to 15 centimetres
0.001cm or 0.1mm
Diameter of a test tube
Digital micrometre screw gauge
Zero to 2.5 centimetres
0.0001cm or 0.001mm
Diameter of a wire
Measuring range
Smallest division
Example of usage