General Physics 1 - Physical Quantities

Precision

a description of how close measurements are to each other.

standard deviation

a measure of how each value in a data set varies or deviates from the mean

derived quantity

a physical aspect describe by a combination of base quantities

random error

adds variability to the data but does not affect average performance for the group

standards

are exact quantities that everyone agrees to use as a basis of comparison

systematic error

caused by any factors that systematically affect measurement of the variable across the sample

accuracy

compares a measurement to the true value

Accuracy

comparing your measurement to the actual or accepted value.

percentage error

defined as the relative error times 100

precision

describes how closely measurements are to each other and how carefully measurements were made

density

how much matter or mass there is in a given amount of space or volume

temperature

measure of kinetic energy of the atoms in an object

Length

measures distance between objects

mass

measures the amount of matter in an object

volume

measures the amount of space something takes up

physical quantities

one that can be measured and consists of a magnitude and unit

Systematic Uncertainties

result from a flaw or limitation in the instrument or measurement technique. Always has the same signs

Random Uncertainties

result from the randomness of measuring instruments. They can be dealt with by making repeated measurements and averaging. One can calculate the standard deviation of the data to estimate the uncertainty.

uncertainty

the degree of doubt that exists about a measured value

absolute error

the difference between the measure value and the true value

base quantity

the essential physical aspects of a measuring system that can be used alone or in combination to describe what is being measured

SI System

the form of measurement typically used by scientists.

weight

the pull of gravity on an object

relative error

the ratio of the absolute error to the true value

Estimation

using your knowledge of something similar in size or amount to determine the size of the new object. Helps to make a rough measurement of an object. Usefully when you are in a hurry and exact numbers are not required.