Measurements and Uncertainties

Question 1

How many fundamental units are in the SI System?

Answer 1

seven

Question 2

What are the SI units?

Answer 2

metre, kilogram, second, ampere, kelvin, mole, candela

Question 3

metre

Answer 3

unit of distance

Question 4

kilogram

Answer 4

unit of mass

Question 5

second

Answer 5

unit of time

Question 6

ampere

Answer 6

unit of electric current

Question 7

kelvin

Answer 7

unit of temperature

Question 8

mole

Answer 8

one mole of substance contains as many particles as there are atoms in 12g of carbon-12

Question 9

candela

Answer 9

unit of luminous intensity

Question 10

order of magnitude

Answer 10

expressing a quantity as a plain power of 10

Question 11

What are the two main types of uncertainty?

Answer 11

systematic and random

Question 12

systematic error

Answer 12

biases in measurements in same directions (always too large or small)
result from technique used to make a measurement

Question 13

random error

Answer 13

repeated measurements of same quantity show spread of values

include reading uncertainties

Question 14

What is the uncertainty in reading an instrument?

Answer 14

+/- half of the smallest width of the graduations on the instument

Question 15

accurate

Answer 15

systematic error in measurement is small

Question 16

precise

Answer 16

random uncertainty in measurement is small

Question 17

What must the value of the average period be expressed?

Answer 17

to same precision as the uncertainty

Question 18

What do the significant figures of result reflect?

Answer 18

level of confidence of results

Question 19

absolute uncertainty

Answer 19

uncertainty of result

Question 20

fractional uncertainty

Answer 20

uncertainty of result / actual result

Question 21

percentage uncertainty

Answer 21

uncertainty of result / actual result x100

Question 22

Q = a + b, Q = a - b uncertainty

Answer 22

absolute uncertianty of Q = sum of absolute uncertainties of a and b

Question 23

Q = ab, Q = a/b

Answer 23

fractional uncertainty of Q = sum of fractional uncertainties of a and b

Question 24

Q = a^n, Q = nth root of a

Answer 24

fractional uncertainty of Q = fractional uncertainty of a x absolute value of n