Sciences Faciles : Du plus simple au plus compliqué, c'est facile
Introduction to IB Physics
,par mousme5Let's have a critical mind
Speed of light? 3x108 m/s, easy. Speed of rotation of the earth? Slightly harder, right? Maybe 100 km/s? 3 050 km/s?... not really, it is in fact of 29,783 km/s ! Do you still think you can make good approximations?
In IB Physics it is very helpful to keep in mind a few figures to be able to spot some of your mistakes.
The biggest range is of 80 orders of magnitudes !
Don't forget... if you have values ranging from 104 to 108, the order of magnitude will be of 4.
Range of distances
Size of a sub-atomic particle: 10-15m
Earth-sun distance: 1,5 x 1011
Size of the visible universe: 1025
It is a range of 40 orders of magnitude.
Range of times (t= distance/speed)
Speed of light: 300 000 000 ms-1 or 3 x 108 ms-1
Time for light to cross a nucleus: 10-23 s
Whole age of the universe: between 9 and 13 billion (1010) years so
1010 x 365,25 x 24 x 60 x 60 = 1018 s
It is a range of 41 orders of magnitude.
Range of masses
Mass of electron: 10-30 kg
Mass of proton: 10-27 kg
Mass of the universe: 1050 kg
It is a range of 80 orders of magnitude.
Range of speed
Non-moving object: 0 ms-1
Highest speed: speed of light
As you have already realized from the following list, in Physics, the numbers are expressed in scientific notation (meaning in powers of ten). Be careful to always put your results in this form!
Finally, scientific notation helps us to define the order of magnitude : "the order of magnitude of a quantity is its right power of ten."
Now that you have read the course, please respond to the QCM to check your understanding !
