physics - kips lecture

Question 1

definition of precision + what is depends on/inversely related to

Answer 1

precision: how close measurements are to each other (consistency of measurements)

• depends on absolute uncertainty
• inversely related to least count

Question 2

absolute uncertainty (+ relative uncertainty)

Answer 2

uncertainty of a measurement, measure of the range of possible values around a measured value

• different from relative uncertainty, which is in relation to the measured value (expressed as a ratio or percentage)

Question 3

least count + in relation to precision

Answer 3

minimum value that an instrument can measure

• instruments with smaller least count have more precision (makes sense because more detailed measurements)

Question 4

accuracy (definition + what it depends on)

Answer 4

accuracy: how close measurement is to actual value

accuracy of measurement depends on the fractional uncertainty or percentage uncertainty

• accuracy is inversely related to fractional uncertainty

Question 5

fractional uncertainty

Answer 5

indicates proportion of measured value that is uncertain

• relative measure of uncertainty or error associated with a measurement

(typically written as a ratio or percentage)

lower the percent uncertainty value, greater the accuracy

Question 6

fractional uncertainty formula

Answer 6

least count / measured value

(for %, just multiply by 100)

Question 7

which of the 3 is the most precise instrument?

• meter rod
• screw gauge
• vernier calipers

Answer 7

screw gauge

Question 8

precision and accuracy depends on what?

Answer 8

precision depends on least count

accuracy depends on % uncertainty

Question 9

physical quantities definition

Answer 9

on the basis of which laws of physics are expressed

• all those quantities that are measured accurately

Question 10

base quantity vs derived quantity

Answer 10

base quantity (fundamental quality): are not defined in terms of other quantities (considered to be independent and cannot be derived from other quantities)

derived quantity: defined/expressed in terms of other quantities (obtained by performing math like add, subtract, divide, multiple one or more base quantities)

ex: speed = distance/time

Question 11

7 base quantities

Answer 11

• length
• mass
• time
• electric current
• temperature
• amount of substance (# of atoms, molecules)
• luminous intensity (intensity of visible light)

Question 12

list 5 examples of derived quantities

Answer 12

are infinite but some examples are:

velocity, acceleration, force, volume, density

Question 13

2 steps in measuring a base quantity (+ ideal standard if what 2 conditions are met)

Answer 13

• choose a standard
• establish a procedure

(ideal standard if accessible [ruler needed so ruler present] and invariable [one min has 60 secs only])