Chapter 1 - Measurements and Units Flashcards
What are the seven fundamental units?
1) Meter(m)
2) Kilogram
3) Seconds(s)
4) Ampere(A)
5) Kelvin(K)
6) Mole(Mol)
7) Candela(cd)
What can be said about the other units such as m/s^2?
They are derived from the fundamental units
What is the definition of the order of magnitude?
Expressing a quantity in a plain power of 10
What are the two types of errors?
Systematic, Random.
Who is responsible for systematic errors
the observer and instrument.
Who is responsible for random errors?
observers.
How are the biases in measurement of systematic errors?
they are always too large or too small.
Give an example of a systematic error-
when you are measuring water from a graduated cylinder, you may read the volume wrong if the cylinder is tilted.
How are random errors revealed?
They are revealed when repeated measurements of the same quantity show a spread of values, some being too large or some being too small.
How are the biases in random errors?
The results are unbiased and unpredictable.
Give an example of a random error.
f a person is running a 100m race and a group of people time it using a stopwatch, some readings will be inaccurate because the individuals started it too early. Other readings may be inaccurate because they started the stopwatch too late.
When is a reading accurate?
When the systematic error is minimal and the reading is close to its true value.
When is a reading precise?
When the random error is small. If an experiment was repeated multiple times, the values will be close together.
Why do we calculate averages?
Averages are the best estimate for the quantity?
What is a rule for averages and uncertainties?
The value of the average period must be expressed as the same precision as the uncertainty.
if we have a value 28± 0.4 cm for the length of a book, what is the name given to 28 ?
the mean or best estimate.
if we have a value 28± 0.4 cm for the length of a book, what is the name given to 0.4?
The absolute uncertainty.
What is the fractional uncertainty?
The ratio of the absolute uncertainty to the mean value.
What is the percentage uncertainty?
The fractional uncertainty multiplied by 100.
What is a rule for adding or subtracting values with uncertainties?
If we need to add or subtract values, we always add uncertainties.
What is a rule for multiplying or dividing values with uncertainties?
If we need to multiply or divide values, the fractional uncertainty of the result is the sum of the fractional uncertainties of the quantities
What is a rule for raising a value to the power n and the value has an uncertainty?
If we need to raise a value to the power n, the fractional uncertainty of the result is the fractional uncertainty of the value multiplied by the absolute value of n
What is a rule for rooting a value to n?
If we need to root a value to n, the fractional uncertainty of the result is the reciprocal of n multiplied by the fractional uncertainty of the value.
