Foundation of physics

Question 1

What are SI units

Answer 1

units which scientists have agreed to use so that they can easily compare their work

Question 2

name the seven units and what they measure

Answer 2

Amps- electricity
Candela -light intensity
Moles - amount of a substance
Seconds - time
Metres - displacement
Kelvin - temperature
Kilograms - mass

Question 3

What are joules in SI units

Answer 3

kgm²s-²

Question 4

What does femto mean

Answer 4

10^-15

Question 5

what does pico mean

Answer 5

10^-12

Question 6

what does nano mean

Answer 6

10^-9

Question 7

what does micro mean

Answer 7

10^-6

Question 8

what does milli mean

Answer 8

10^-3

Question 9

what does kilo mean

Answer 9

10^3

Question 10

what does mega mean

Answer 10

10^6

Question 11

what does giga mean

Answer 11

10^9

Question 12

what does tera mean

Answer 12

10^12

Question 13

what does peta mean

Answer 13

10^15

Question 14

what’s the equation of a line

Answer 14

y=mx+c

Question 15

what are micrometers and Vernier calipers used for

Answer 15

micrometers to measure 0.01mm
calipers for 0.1mm

Question 16

what is the resolution of micrometers

Answer 16

0.01mm or one hundredth of a mm

Question 17

what is (usually) the resolution of vernier calipers

Answer 17

0.1mm (one tenth of a mm)

Question 18

how do you read the scale on micrometers

Answer 18

read the mm mark to the left of the thimble, write down the mms
check if there is a half mm mark before the mm mark, if so add 0.5 to the previous value
read the scale of the thimble where the mm line meets the line on the thimble to find out how many hundredths of a mm to add to your value
(if the line is between hundredths of a mm, write down the lower value)

Question 19

how do you read the scale on vernier calipers

Answer 19

read the first cm value on the main scale to the left of the vernier scale, write it down
then read the first mm value to the left of the vernier scale on the main scale, add it to the cm value
on the vernier scale, find where the lines on both scales align, this is the tenth of a mm value, add it to the other value to get the final reading

Question 20

what does the ratchet do on micrometers

Answer 20

prevents the object being measured from being compressed out of shape

Question 21

how can you take an accurate measurement of an objects diameter

Answer 21

repeat the measurement 5 times at different angles of the object and calculate a mean

Question 22

what does resolution mean

Answer 22

the smalled possible value that a piece of equipment is able to measure up to

Question 23

what does uncertainty mean

Answer 23

the interval in which the true value can be expected to lie

Question 24

what is the absolute uncertainty for a single reading

Answer 24

the smallest division of the value (1, 0.1, 0.01) with a plus minus sign in front of it

Question 25

how can you find the absolute uncertainty for a range of values

Answer 25

(the greatest value - the smallest value) ÷ 2

Question 26

how can you calculate percentage uncertainty

Answer 26

(absolute uncertainty ÷ mean value) × 100

Question 27

what do you do with the uncertainties when adding or subtracting values

Answer 27

add the **absolute** uncertainties (even if subtracting)

Question 28

what do you with the uncertainties when multiplying or dividing values

Answer 28

find the percentage uncertainties first add the **percentage** uncertainties (don't subtract)

Question 29

what happens to the uncertainty when a value is raised to a power

Answer 29

you must find the percentage uncertainty then you multiply it by the power (don't raise it to the power)

Question 30

what do you do to the uncertainty when multiplying by a constant

Answer 30

Multiply the absolute uncertainty by that constant but not the percentage uncertainty.

Question 31

on which axis do the independant and dependant variables go

Answer 31

independant on x dependant on y

Question 32

how can you represent uncertainty on a graph

Answer 32

When you plot points, draw error bars above and below each point connect the highest point on the first point to the lowest point on the last point (or vice versa) you can then calculate a gradient from the line of worst fit.

Question 33

how can you calculate percentage uncertainty from a graph

Answer 33

((best gradient-worst gradient)÷best gradient)×100 OR ((best y intercept-worst y intercept)÷best y intercept)×100

Question 34

how can you calculate the percentage difference to find the accuracy of your results

Answer 34

((actual value - your value)÷actual value)×100

Question 35

define a scalar

Answer 35

a quantity with only magnitude not direction

Question 36

define a vector

Answer 36

a quantity with magnitude as well as direction

Question 37

how can you calculate a resultant vector from 2 vectors

Answer 37

dram a resultant rector triangle use pythagoras' to find the magnitude then use trig to find the direction

Question 38

what rules must you follow when drawing a vector triangle

Answer 38

the lines must be cyclical the ends of each vector can't touch

Question 39

what does it mean to resolve a vector

Answer 39

to find the magnitude of the vectors it is comprised of