1 - Measurements and units Flashcards
What is a physical quantity made of?
A number and a unit
What should be included in the stages of a calculation?
Units
What is scientific notation (standard form)?
A way of writing numbers using a decimal number multiplied by a power of 10 (eg: 3.20 * 10^5)
What are SI units?
A system of units used by most scientists
What are some SI base units for different categories?
Mass - kilogram; time - second; length - metre; electric current - ampere; temperature - kelvin
What is mass and its properties?
Measure of quantity of matter in object, greater the mass, greater the gravitational attraction of Earth on it and object resists changing speed or direction more
How is 1 metre defined?
Distance travelled by light in a vacuum in 1 / 299,792,458th of a second
What are the different prefixes which can be added to units to change their values and how?
G (giga) - 10^9; M (mega) - 10^6, k (kilo) - 10^3; d (deci) - 10^-1; c (centi) - 10^-2; m (milli) - 10^-3; µ (micro) - 10^-6; n (nano) - 10^-9
What are ways of measuring length?
Using a rule, using calipers if rule can’t be placed right next to object, use tape for lengths of several metres, use laser tape measure
What are ways of measuring time and what needs to be done?
Stopclock, stopwatch, with analogue or digital display, account for zero error
How much is a litre (L)?
1 L = 1000 mL (millilitre), 1000 cm^3 (centimetre cubed), 1 dm^3 (decimetre cubed)
What is the density (kg/m^3) of air?
1.3
What is the density (kg/m^3) of expanded polystyrene?
14
What is the density (kg/m^3) of wood (beech)?
750
What is the density (kg/m^3) of petrol?
800
What is the density (kg/m^3) of ice (0℃)?
920
What is the density (kg/m^3) of polythene?
950
What is the density (kg/m^3) of water (4℃)?
1000
What is the density (kg/m^3) of concrete?
2,400
What is the density (kg/m^3) of glass (varies)?
2,500
What is the density (kg/m^3) of granite?
2,700
What is the density (kg/m^3) of aluminium?
2,700
What is the density (kg/m^3) of steel (stainless)?
7,800
What is the density (kg/m^3) of copper?
8,900
What is the density (kg/m^3) of lead?
11,400
What is the density (kg/m^3) of mercury?
13,600
What is the density (kg/m^3) of gold?
19,300
What is the density (kg/m^3) of platinum?
21,500
What is the density (kg/m^3) of osmium?
22,600
What are the ways of measuring volume?
Measuring cylinder, calculation, see rise in liquid in measuring cylinder, displacement can
What are the ways of measuring density?
Calculation, hydrometer (for liquids)
What is the average density of the Earth?
5520 kg/m^3
What is the average density of Jupiter?
1330 kg/m^3
What is the formula for speed?
Average speed (v) = distance moved (s) / time taken (t)
What is the SI unit of speed?
m/s
What is velocity and its difference from speed?
Velocity means the speed of something and its direction of travel
What are vectors?
Quantities with a magnitude and a direction
What is the formula for acceleration?
Average acceleration (a) = change in velocity (Δv) / time taken (Δt)
What is a negative acceleration called?
Deceleration or retardation
What is the SI unit of acceleration?
m / s^2
What are important properties of speed-time and distance-time graphs?
On a distance-time graph, the gradient of the line is equal to the speed; on a speed-time graph, the gradient of the line equals acceleration and the area under the line equals the distance travelled
What can a ticker-tape timer be used for?
