Physics - Units and Prefixes

2020-09-07
3 min read

Units and Prefixes

Units and Prefixes are a simple topic but very important and foundational for the rest of physics as a whole. It’s one of those things that are important learning because it improves fluency in thought involving physics problems and having a good conceptual understanding of what the units actually represent can also be helpful.

Units

What are the two types of units??
  • Base units
  • Compound units
What is a base unit??

Standard units of measurement from which all other SI units are derived.

What is a compound unit??

An SI unit created from a combination of base units.

What are the 6 base units??
  • metre
  • kilogram
  • second
  • Ampere
  • Kelvin
  • Mole
How do base units relate to base quantities??

Base units are standard units of measurement for the base quantities.

What are the 6 base quantities??
  • length
  • mass
  • time
  • electric current
  • absolute temperature
  • amount of substance
What is the base unit of mass??

kilogram, [$]kg[/$]

What is the base unit of length??

metre, [$]m[/$]

What is the base unit of time??

second, [$]s[/$]

What is the base unit of current??

ampere, [$]A[/$]

What is the base unit of temperature??

kelvin, [$]K[/$]

What is the SI unit of potential difference??

volt, [$]V[/$]

What is the SI unit of density??

kilogram per metre cubed, [$]kgm^{-3}[/$]

What is the SI unit of energy??

joule, [$]J[/$]

What is the SI unit of power??

watt, [$]W[/$]

What is the SI unit of charge??

coloumb, [$]C[/$]

Q: What is [$]1m^2[/$] in [$]mm^2[/$]??

[$]10^6mm^2[/$]

Q: What is [$]1m^3[/$] in [$]cm^3[/$]??

[$]10^6cm^3[/$]

Q: What is [$]1km^2[/$] in [$]m^2[/$]??

[$]10^6m^2[/$]

Q: What is [$]1cm^3[/$] in [$]mm^3[/$]??

[$]10^3mm^3[/$]

Q: There are [$]10^24[/$] free charge carriers per [$]m^3[/$] of material. How many are there per [$]mm^3[/$]??

[$]10^15[/$]

Q: [$]10^6[/$] particles strike each [$]mm^2[/$] of a surface per second. How many strike [$]1m^2[/$] of the surface per second??

[$]10^12[/$]

Q: If there is 1 particle per [$]mm^2[/$], how many are there per [$]m^3[/$]??

[$]10^9[/$]

Q: Water has a density of [$]1000kgm^-3[/$]. What is this in [$]kgcm^{-3}[/$]??

[$]10^{-3}[/$]

Q: Water has a density of [$]1000kgm^-3[/$]. What is this in [$]gcm^{-3}[/$]??

[$]1[/$]

Units

What is the value of the prefix T (tera)??

[$]10^12[/$]

What is the prefix for [$]10^12[/$]??

T, tera

What is the value of the prefix G (giga)??

[$]10^9[/$]

What is the prefix for [$]10^9[/$]??

G, giga

What is the value of the prefix M (mega)??

[$]10^6[/$]

What is the prefix for [$]10^6[/$]??

M, mega

What is the value of the prefix k (kilo)??

[$]10^3[/$]

What is the prefix for [$]10^3[/$]??

k, kilo

What is the value of the prefix d (deci)??

[$]10^{-1}[/$]

What is the prefix for [$]10^{-1}[/$]??

d, deci

What is the value of the prefix c (centi)??

[$]10^{-2}[/$]

What is the prefix for [$]10^{-2}[/$]??

c, centi

What is the value of the prefix m (milli)??

[$]10^{-3}[/$]

What is the prefix for [$]10^{-3}[/$]??

m, milli

What is the value of the prefix [$]\mu[/$] (micro)??

[$]10^{-6}[/$]

What is the prefix for [$]10^{-6}[/$]??

[$]\mu[/$], micro

What is the value of the prefix n (nano)??

[$]10^{-9}[/$]

What is the prefix for [$]10^{-9}[$]??

n, nano

What is the value of the prefix p (pico)??

[$]10^{-12}[/$]

What is the prefix for [$]10^{-12}[/$]??

p, pico

What is the first step in using a variable with a prefix??
  • Replacing the prefix symbol with its equivalent multiplier.
  • e.g. [$]0.16\muA = 0.16 \times 10^{-6}A[/$]
Q: What is [$]1.4kW[/$] without a prefix??

[$]1.4\times10^3 W[/$]

Q: What is [$]340MW[/$] without a prefix??

[$]3.4\times10^8 W[/$]

Q: What is [$]46pF[/$] without a prefix??

[$]4.6\times10^{-11}[/$]

Q: What is [$]6.4\times10^{-3}[/$] with a prefix??

[$]6.4mW[/$]

Q: What is [$]0.520\times10^4 \ohm[/$] with a prefix??

[$]5.2k\ohm[/$]

How many $cm^3$ in $1\quad\text{litre}$??

$$ 1000cm^3 $$

How many $m^3$ in $1\quad\text{litre}$??

$$ 10^{-3}m^3 $$


Metadata
date: 2020-09-07 17:11
tags:
- '@?ankify'
- '@?physics'
- '@?year-1'
- '@?public'
title: Physics - Units and Prefixes