2.1.2 Estimating Physical Quantities Flashcards

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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.

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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.

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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.

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4
Q

Name three methods of estimation and produce an example for each.

A
  1. 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.
  2. 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.
  3. By method of assumption:
    Assuming an apple to be spherical.
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