IB Physics: Range of magnitudes of quantities in our universe

IB Physics: Range of magnitudes of quantities in our universe

Range of magnitudes of quantities in our universe

1.1. State and compare the quantities to the nearest order of magnitude.

Orders of magnitude are basically how large values are. For example if the length of a table is 2 metres, the order of magnitude would be 100. This is because 100 is equal to 1, and it has the same amount of digits as the value of the length, 2 metres. Similarly a value of 400 would have an order of magnitude of 102 because this equals 100. All orders of magnitudes are written in powers of 10 so we can compare them easily with others and to get an idea of the scale of the number.

1.2 State the ranges of magnitude of distances, masses and times that occur in the universe, from smallest to greatest.

The IB course requires you to know a few orders of magnitude so you just have to learn them.
Distances:
Sub-nuclear particles: 10-15 m
Extent of the visible universe: 1025 m
Masses:
Mass of electron: 10-30 kg
Mass of universe: 1050 kg
Times:
Passage of light across a nucleus: 10-23 s
Age of the universe : 1018 s

1.3 State ratios of quantities as differences of orders of magnitude.

Using orders of magnitude makes it easy to compare quantities. For example, if we want to compare the size of an atom (10-10 m) to the size of a single proton (10-15 m) we would take the difference between the powers to obtain the ratio. Here, the difference is of magnitude 105meaning that an atom is 105 or 100000 times bigger than a proton.

Make sure your essay is 100% unique

Our experts will write for you an essay on any topic, with any deadline and requirements from scratch

127 our experts are available
right now

Get custom essay

1.4 Estimate approximate values of everyday quantities to one or two significant figures and/or the nearest order of magnitude.

• Significant figures

To express a value to a certain amount of significant figures means to arrange the value in a way that it contains only a certain amount of digits which contribute to its precision.
For example, if we were asked to state the value of an equation to three significant figures and we found the result of that value to be 2.5423, we would state it as 2.54.
The amount of significant figures includes all digits except leading and trailing zeros (such as 0.0024 (2 sig. figures) and 24000 (2 sig. figures)) which serve only as placeholders to indicate the scale of the number.

• Rules for identifying significant figures:

All non-zero digits are considered significant (such as 14 (2 sig. figures) and 12.34 (4 sig. figures)).
Zeros placed in between two non-zero digits (such as 104 (3 sig. figures) and 1004 (4 sig. figures))
Trailing zeros in a number containing a decimal point are significant (such as 2.3400 (5 sig. figures) note that a number 0.00023400 also has 5 sig. figures as the leading zeros are not significant). In the first case the zeros at the end of the number are there to indicate the degree of accuracy the value has.
Another thing to note is that some numbers with no decimal point but ending in trailing zeros can cause some confusion. For example, the number 200, this number contains one significant figure (the digit 2). However, this could be a number that is represented to three significant figures which just happens to end with trailing zeros. In which case it is important to indicate which of them are significant numbers are by placing something like (2 s.f) behind the number to avoid confusion.

• Expressing significant figures as orders of magnitude:

To represent a number using only the significant digits can easily be done by expressing it’s order of magnitude. This removes all leading and trailing zeros which are not significant. This is the same as writing a number in standard form. For example 0.00034 contains two significant figures (34) and fours leading zeros in order to show the magnitude. This can be represented so that it is easier to read as such: 3.4 x 10-4.
Rounding is very simple and the same as GCSE Maths. 5 or higher is rounded up, lower than 5 is rounded down.