Practical Skills/Foundation Flashcards
vernier scale
type of scale used on micrometers reading from a fixed scale and a moving scale
reproducible
different experimenter, same method, different equipment
repeatable
same experimenter, same methods, same equipment
fiducial marker
A thin marker, such as a splint, that is used to ensure readings are taken from the same place each time. They are used to improve the accuracy of measurements.
independent variable
the variable that is changed
dependent variable
the variable that is measured
control variable
the condition that is kept constant
Why do repeat readings?
Can spot anomalous results more easily and reduce the effect of random error
What does precise mean?
How close the readings are to each other with a particular instrument. The more precise, the more decimal places the value is.
What does reliable mean?
How small the range of data spread is. The more reliable, the closer together they all are.
What does valid result mean?
all control variables are controlled and experiment answers question with precise data.
What does accurate mean?
result is close to true answer.
What is the uncertainty for a measuring instrument?
half of the smallest measurement it can measure
What do we need to note about measuring lengths?
equipment uncertainty doubled because there is uncertainty at each end of the ruler.
What is absolute uncertainty?
the total uncertainty of a measurement
What is percentage uncertainty?
the uncertainty given as a percentage of the measurement.
What is the assumed uncertainty?
half the increment of the last significant figure. e.g. 2.0 is 0.05.
Name the 6 SI base units
kilogram, metre, second, ampere, kelvin, mole
what is a systematic error
shifts all the values by the same amount
what causes systematic error?
parallax, calibration, lining up of a ruler, not zeroing the scale
what is a random error?
parallax, human error
How to combine uncertainties?
add/subtract - add ab
multiply/divide - add %
powers - multiply % by power
What is percentage difference?
Difference between experimental and actual value given as a percentage of actual value
what is a scalar?
the magnitude of something - no direction
what is a vector?
something with magnitude and direction
How to draw worst line?
from top of top error bar to bottom of bottom error bar.
Are energy and power vectors or scalars?
vectors
Why are values for average speed and velocity different?
one vector, one scalar, displacement always in a straight line which is less than or equal to distance
