2 - Foundations of physics Flashcards
What are SI units
Fundamental (base) units of phyiscal quantities
What are the SI units of mass
kg
What physical quantity is measured in mol?
Amount of substance
What is the SI unit of current?
Amperes
A
Is the SI unit for temperature °C or K
K (kelvin) as this is the absolute scale
What is the SI unit of length?
Metres - m
What quantity is measured in seconds?
Time
Are newtons an SI unit
No, newtons are not fundamental, the SI units for force are kgms^-2 (since F=ma)
Derive the. SI units for energy
E=1/2mv^2
units = kg m^s s^-2
Derive the SI units of force
Force = mass x acceleration Units = Kgms^-2
Express 60 T Ω in standard form
60 x 10^12
Write 0.000003m with a suitable prefix
3μm (3x10^-6m)
What is accuracy?
Accuracy is a measure of how close a measured value is to the true accepted value
What is validity?
A measurement is valid if it measures what it is supposed to be measuring. An experimental procedure is valid if the obtained values provide an answer to the question that is being asked
What is random error
An error that occurs due to unexpected changes during an experiment> These cannot be predicted and they can cause repeated results to differ from one to another
What is an anomaly?
An anomaly (also know as an outlier) is a data point or value in a set of results that does not fit the trend of the data and is therefore an unexpected result. These can happen as a result of random errors during an experiment
What is a systematic error?
An error that occurs due to faults in equipment or equipmental method. Systematic errors cause the result to differ by the same amount each time, making them predictable. They can occur due to not callibrating an instrument correctly
What is precision?
How consistent/close together repeat readings are - the closer they are, the more precise they are
What is meant by resolution?
The smallest change in the quantity being measured that gives a recognisable change in reading
e.g on a ruler the resolution is 1mm
What is absolute uncertainty?
Uncertainty given as a fixed quantity
What is an order of magnitude
Powers of ten which describe the size of an object and which can also be used to compare the sizes of objects
What is meant by a scalar quantity?
A quantity that only has magnitude
What is a vector quantity?
A quantity that has magnitude as well as direction
