Physical Quantities, Units and Measurements Flashcards
Precision of Metre Rule/Measuring Tape
0.1cm
Precision of Digital Vernier Calipers
0.001cm
Precision of Digital Micrometer Screw Gauge
0.0001cm
Precision of Atomic Clock
10⁻¹⁰ s
Precision of Digital Stopwatch
+/- 0.01s
Precision of Analogue Stopwatch
+/- 0.1s
Precision of Ticker-tape timer
0.02s
Human reaction time
200ms
Purpose of Inside Jaws of Digital Vernier Calipers
To measure the internal diameter of objects
Purpose of Outside Jaws of Digital Vernier Calipers
To measure external diameter/width of objects
Purpose of Tail of Digital Vernier Calipers
To measure depth of objects
Purpose of Spindle in Digital Micrometer Screw Gauge
To measure diameter of objects
Purpose of Ratchet in Digital Micrometer Screw Gauge
To adjust the spindle to ensure spindle is in contact with object
What does a Metre Rule/Measuring Tape measure?
It measures a person’s waist/height of table
What does a Digital vernier Caliper measure?
It measures the diameter of test tube
What does a Digital Micrometer Screw Gauge measure?
It measures the diameter of a wire
What is a Random Error?
Random Errors are unpredictable and cluster around a mean value
What is a Systematic Error?
Systematic Errors are constant and predictable
How to minimise Random Errors?
Random Errors can be minimised by taking several readings and taking the average
How to avoid Systematic Errors?
Systematic Errors can be avoided by calibrating equipment, which if not corrected, can lead to values far from true value
What causes Parallax Error?
Parallax Error is caused when our eyes are positioned such that our line of sight is not perpendicular to the ruler
Why do we avoid using zero mark as start point for measurements?
As wear and tear makes it unsuitable for measuring purposes and it may introduce errors to readings
Example of Random Error
Human reaction time
Example of Systematic Error
Always reads from the top of the meniscus instead of the bottom
Examples of Scalar Quantities
Distance, Speed, Mass, Energy, Time
Examples of Vector Quantities
Displacement, Velocity, Weight, Acceleration, Force
SI Unit for Length
Metres
SI Unit for Mass
Kilograms
SI Unit for Time
Seconds
SI Unit for Electric Current
Ampres
SI Unit for Thermodynamic Temperature
Kelvin
SI Unit for Amount of Substance
Mol
Prefixes
Tera: 10¹² (T)
Giga: 10⁹ (G)
Mega: 10⁶ (M)
Kilo: 10³ (k)
Deci: 10⁻¹ (d)
Centi: 10⁻² (c)
Milli: 10⁻³ (m)
Micro: 10⁻⁶ (µ)
Nano: 10⁻⁹ (n)
Pico: 10⁻¹² (p)
What is One Complete Oscillation of a Pendulum?
1 complete to-and-fro motion of pendulum
What is the Period of a Pendulum?
Time taken for 1 complete oscillation
What affects/does not affect the Period of a Pendulum?
Mass of bob does not affect period
Gravitational field strength and length of pendulum affects period
How to measure One Complete Oscillation of a Pendulum?
Measure time for 20 oscillations and divide by 20
