Question

Physics question

1.What is the precision of a meter stick? The Vernier calipers? The micrometer calipers? If we measure an object of length approximately 2cm, what is the relative uncertainty if we use each of the above instruments?

2.

2. You will compute a quantity, λ, (2-1) Write eq 2-1 in the form of eq 1-9 as follows: λ=h/H and use eq 1-10 to write the standard deviation in λ as a function of h and H and their standard deviations.

Answer 1

In scientific measurements Precision refers to the closeness of two or more Solution: measurements to each other. In lab if measure a length of a thread four times, and get 3.6 cm each time, then our measurement is very precise. Precision is independent of accuracy. We may be very precise but not accurate, we may also be accurate but imprecise. Accuracy refers to the closeness 1 Meter Stick of a measured value to a standard or known value. For example, in lab if we obtain a weight measurement of 12.4 gm for a given substance, but the actual or known weight is 15 gm, then our measurement is not accurate. In this case, the measurement is not close to the known value Precision level or precision of an instrument is the measurement up to decimal place that an instrument has ability to measure Vernier Caliper 1112 13 The smallest length we measure with a meter stick is 1mm. So its precision is 1mm. A standard Vernier caliper has the precision of 0.1 mm or 0.05 mm. A micrometer caliper has the precision of 0.01 mm If we measure length 2 cm with meter stick it can be up to 2 0.1cm. Hence the relative Micrometer Caliper 1mm x100% Imix100%=5%. 2cm uncertainty for this measurement by meter stick is Rvs 20mm If we measure length 2 cm with meter stick it can be up to 2±0.01cm. Hence the relative uncertainty for this measurement by meter stick is 0.1m 100%s Im x100%= 0.5% Ryc 2cm 200mm If we measure length 2 cm with meter stick it can be up to 2 0.001cm. Hence the relative uncertainty for this measurement by meter stick is 0.01mm100% = 1mm RMC x100% 0.05% 2cm 2000mm