Expressing Quantities & SI Units Flashcards

All 14 cards in this deck

What does the prefix giga (G) mean?

$\times 10^9$ (1 000 000 000).
e.g. 1 GW = 1 000 000 000 W

What does the prefix mega (M) mean?

$\times 10^6$ (1 000 000).
e.g. 1 MW = 1 000 000 W

What does the prefix kilo (k) mean?

$\times 10^3$ (1000).
e.g. 1 kJ = 1000 J

What does the prefix milli (m) mean?

$\times 10^{-3}$ (one thousandth).
e.g. 1 mA = 0.001 A

What does the prefix micro ($\mu$) mean?

$\times 10^{-6}$ (one millionth).
e.g. 1 $\mu$s = 0.000 001 s

What does the prefix nano (n) mean?

$\times 10^{-9}$ (one thousand millionth).
e.g. 1 nm = 0.000 000 001 m

How do you convert a time in hours into seconds?

Multiply by 3600 ($60 \times 60$).
To go back from seconds to hours, divide by 3600.

How do you convert a speed in km/h into m/s?

Multiply by 1000 (km to m), then divide by 3600 (hours to seconds) — the same as dividing by 3.6.

What is standard form?

A number written as $A \times 10^n$, where $1 \le A < 10$.
e.g. $4500 = 4.5 \times 10^3$

True or false? $2.5 \times 10^{-3}$ written as an ordinary number is 0.0025.

True. A negative power of 10 moves the digits that many places to the right.

When counting significant figures, which digit do you start from?

The first non-zero digit. e.g. in 0.04863 the first significant figure is the 4.

If every measurement in a question is given to 2 significant figures, to how many significant figures should you give your calculated answer?

2 significant figures — match the number of significant figures in the data given.

What does the prefix centi (c) mean?

$\times 10^{-2}$ (one hundredth).
e.g. 1 cm = 0.01 m

What are the SI base units of mass, length and time?

Mass: kilogram (kg); length: metre (m); time: second (s). The base unit of mass is the kg, not the g.