Physics T1: Physical quantities, units and measurement

Define the term physical quantity

- Quantity that can be measured

- Consists of a numerical magnitude and unit

State the SI unit for length

Metre, m

State the SI unit for mass

Kilogram, kg

State the SI unit for time

Seconds, s

State the SI unit for electric current

Amphere, A

State the SI unit for temperature

Kelvin, K

State the SI unit for amount of substance

Mole, mol

State the SI unit for luminous intensity

Candela, cd

State the factor of prefix Tera

10^12

State the factor of prefix Giga

10^9

State the factor of prefix Mega

10^6

State the factor of prefix Kilo

10^3

State the factor of prefix deci

10^-1

State the factor of prefix centi

10^-2

State the factor of prefix milli

10^-3

State the factor of prefix micro

10^-6

State the factor of prefix nano

10^-9

Define the term precision

Smallest unit an instrument can measure

State the smallest division of a metre ruler

1mm

State the smallest division of a tape measure

1mm

State the smallest division of a digital caliper

0.01mm

State the smallest division of a digital micrometer screw gauge

0.001mm

State the characteristics of random error

- Unpredictable

- Clusters around a mean value

Describe how random error can be minimized

- Take several readings and find the average

State 2 examples of random error

- Reaction time error

- Parallax error(when viewed from different angles)

State the characteristic of systematic error

- Constant & predictable

Describe how systematic error can be minmized

- Calibrate the instrument

State 2 examples of systematic error

- Zero error

- Parallax error(when viewed from the same angle)

Describe the differences between speed and velocity

Speed:

- Distance over time

- Scalar

Displacement

- Displacement over time

- Vector

Define the term scalar quantity

Physical quantities that only have magnitudes

Define the term vector quantity

Physical quantities that have magnitude and direction

State the SI unit for speed and velocity

m/s

State 5 examples of scalar quantities

DSMET

- Distance

- Speed

- Mass

- Energy

- Time

State 5 examples of vector quantities

DVAFW

- Displacement

- Velocity

- Acceleration

- Force

- Weight

Define the term oscillation of a pendulum bob

The repeated movement of a pendulum bob

Define the term period of a pendulum bob

Time taken for pendulum bob to complete one oscillation

Describe the process of measuring the period of a pendulum bob

- Measure time(t) for 10-20 oscillations

- Divide t by number of oscillations to find period(T)

State the variable(s) that affect the period(T) of a pendulum bob

- T is only dependent on the length of the string

- As the length of the string increases, T increases

State the order of magnitude of the diameter of the earth

10Mm

State the order of magnitude of the diameter of an atom

0.1nm

State the order of magnitude of the diameter of human hair

0.1mm

State the order of magnitude of a cell membrane

10nm

State the order of magnitude of the length of a bacterium

1 micrometer

State the order of magnitude of a piece of copper wire

1cm