units and uncertainty

Question 1

list the 7 base units

Answer 1

mass - kilogram
length - metre
time - second
temperature - kelvin
current - amp
light intensity - candela
amount of substance - mole

Question 2

express the base units of magnetic flux density

Answer 2

F = BIL
B = F/(IL)
= N/Am
= (kgms^-2)/Am
= kg(A^-1)(s^-2)

Question 3

express the base units of spring constant

Answer 3

F = kx
k = F/x
= N/m
= (kgms^-2)/m
= kgs^-2

Question 4

define systematic errors

Answer 4

a predictable error that can be measured and removed from measurements

Question 5

Define random error

Answer 5

an error that cannot be predicted and can only have its effects reduced by measuring repeat readings and calculating an average

Question 6

define precision

Answer 6

the number of decimal places to which a measurement is stated

Question 7

define resolution

Answer 7

the smallest division on a measuring instrument

Question 8

define sensitivity

Answer 8

the smallest detectable change in conditions using an instrument

Question 9

Define accuracy

Answer 9

how close a measurement is to the true value

Question 10

uncertainty in a measurements from an analogue measuring device

Answer 10

half of the resolution of the measuring device

Question 11

uncertainty in a measurement from a digital measuring device

Answer 11

resolution of the measuring device

Question 12

uncertainty in an average value is calculated using

Answer 12

(range of repeated reading) / 2

Question 13

uncertainty in a gradient is calculated by

Answer 13

drawing a line of best fit and worst fit.
Find the difference between the gradients of the 2 lines

Question 14

uncertainty in a y-intercept/x-intercept is calculated by

Answer 14

drawing a line of best fit and worst fit.
Find the difference between the y-intercepts/x-intercepts of the 2 lines

Question 15

scalar

Answer 15

property that has only magnitude

Question 16

vector

Answer 16

a property that has both magnitude and direction