02 Foundations of Physics

Question 1

physical quantity

Answer 1

property of an object or phenomenon that can be measured

Question 2

International System of Units (SI)

Answer 2

standard system of units used by scientists which consists of 7 base units

Question 3

6 base units used at A Level

Answer 3

metre (m)
kilogram (kg)
second (s)
ampere (A)
kelvin (K)
mole (mol)

Question 4

degrees celsius to kelvin

Answer 4

add 273

Question 5

prefix: peta

Answer 5

P
10^15

Question 6

prefix: tera

Answer 6

T
10^12

Question 7

prefix: giga

Answer 7

G
10^9

Question 8

prefix: mega

Answer 8

M
10^6

Question 9

prefix: kilo

Answer 9

k
10^3

Question 10

prefix: deci

Answer 10

d
10^-1

Question 11

prefix: centi

Answer 11

c
10^-2

Question 12

prefix: milli

Answer 12

m
10^-3

Question 13

prefix: micro

Answer 13

µ
10^-6

Question 14

prefix: nano

Answer 14

n
10^-9

Question 15

prefix: pico

Answer 15

p
10^-12

Question 16

prefix: femto

Answer 16

f
10^-15

Question 17

derived quantity

Answer 17

a quantity that comes from a combination of base units

Question 18

derived unit

Answer 18

a unit used to represent a derived quantity
eg N for force

Question 19

newton N in base units

Answer 19

kgms^-2

Question 20

joule J in base units

Answer 20

kgm^2s^-2

Question 21

how to find base units

Answer 21

use equations expressing derived quantities as base quantities and replace the quantities with the units (ignore any numeric values that do not have units eg 1/2 in Ek=1/2mv^2)

Question 22

homogenous

Answer 22

identical

Question 23

true value

Answer 23

value that would be obtained in an ideal measurement

Question 24

(measurement) error

Answer 24

difference between a measured value and the true value of a quantity being measured

Question 25

random error & how to correct

Answer 25

measurement errors where measurements vary unpredictably cannot be corrected, but effect can be reduced by taking multiple measurements and calculating mean

Question 26

systematic error & how to correct

Answer 26

measurements differ from true value by a consistent amount each time find the value by which the measurements differ from the true value and add value to recorded measurements

Question 27

zero error

Answer 27

type of systematic error: measuring device does not read zero when it should

Question 28

accuracy

Answer 28

how close a measurement is to the true value - the closer, the more accurate

Question 29

precision

Answer 29

how close repeated measurements are to each other - the closer, the more precise

Question 30

uncertainty

Answer 30

an interval in which the true value of a measurement can be expected to lie

Question 31

absolute uncertainty

Answer 31

+/- half the range

Question 32

percentage uncertainty

Answer 32

(absolute uncertainty) / (mean value) * 100

Question 33

adding / subtracting uncertainties

Answer 33

add the absolute uncertainties of each value

Question 34

multiplying / dividing uncertainties

Answer 34

add percentage uncertainties of each value

Question 35

raising uncertainties to a power

Answer 35

when a value is raised to n, percentage uncertainty is multiplied by n

Question 36

resolution

Answer 36

smallest change a measuring instrument can detect

Question 37

reading a micrometer

Answer 37

Read the sleeve measurement (resolution 0.5mm) then read the thimble measurement (resolution 0.01mm) and add the thimble measurement that aligns with the sleeve scale line to the sleeve measurement

Question 38

reading a vernier caliper

Answer 38

read the cm value either lined up with (or if not lined up, to the left of) the zero line on the vernier scale. Them find the vernier scale line that best lines up with a line on the cm scale, and add this vernier scale measurement to the already attained cm measurement