2.1.2 Estimating Physical Quantities Flashcards
1
Q
What is a reasonable estimation?
A
One with the correct order of magnitude (to 1sf), units and on that can be mentally performed if required.
2
Q
Why estimate? Produce an example.
A
If the estimated quantity cannot be measured directly, it should be done by means of comparison - eg: the width of a note as the same as the width of a piece of paper.
3
Q
How do you ensure that an estimation is to the correct order of magnitude?
A
Round your value to the nearest power of 10; thus it should be accurate to the correct order of magnitude.
4
Q
Name three methods of estimation and produce an example for each.
A
- By method of ratio:
How much larger is the mass of DNA compared to a proton? These values will be given in some form of standard form, and so do the ratios of this standard form power. 10^-18:10^-27 would mean the RHS is 10^9 times heavier. - By method of comparison:
use the thickness of a £10 note as the thickness of a piece of paper, because they are comparable and ne cannot be measured. - By method of assumption:
Assuming an apple to be spherical.