1 / 8

Estimation

Estimation. Rounding. The simplest estimation technique is to round. This works very well on formulas where all the values can be reduced to one significant figure. Order of Magnitude Rounding. Rounding to a power of ten is the crudest form of rounding.

ovidio
Télécharger la présentation

Estimation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Estimation

  2. Rounding • The simplest estimation technique is to round. • This works very well on formulas where all the values can be reduced to one significant figure.

  3. Order of Magnitude Rounding • Rounding to a power of ten is the crudest form of rounding. • Order of magnitude estimates are easy to compare since they are all only powers of ten. • For a comparison to work, the units need to be the same (meters and meters, not km).

  4. How Big? • Assume the density of a rock is three times that of water. How many centimeters across is a one metric ton (1000 kg) rock? • The rock has a density of 3 g/cm3 so the volume is 106 g / (3 g/cm3) = 3.3 x 105 cm3. • Estimate that the rock is a sphere, V = (4/3) r3 • d = 2r = 2 (3V/4 )1/3 • d = 85.7 cm  90 cm

  5. Using Geometry • Geometrical shapes can often be used to approximate real shapes. • The standard formulas from geometry can be used to make an estimate. • Shapes can be 2-dimensional (triangle, circle) • Or 3-dimensional (box, sphere).

  6. Equal ratios Right triangles Triangles s2 r s s1 q h1 h2 t

  7. angle A base angle B Apparent Shift • A moving observer sees fixed objects move. • Near objects appear to move more than far objects. • Telephone poles whip by faster than distant trees. • The effect is due to the change in observation point, and is used by our eyes for depth perception.

  8. 0 5 10 15 20 25 30 35 40 45 50 Observing Parallax • Observe an object against the background. • Shift one seat left and observe again. • Subtract to get the parallax shift. next

More Related