Physical Quantities & Units Flashcards
A property of a material or system that can be obtained and quantified by measurement indicating the appropriate base and unit
Physical Quantity
Can be expressed as a value consists of numerical magnitude and the unit in which it is measure: 3.9 grams, 50.0 dL, 19.3g/cm³
Physical Quantity
can be expressed as a value of certain unit: grams, kilograms, or pounds
Physical Quantity
An operation by which an unknown physical quantity is compared with a known quantity based on standard
Measurement
Using your idea of something similar in size or amount to determine the size of the new object
Estimation
Helps to make a rough measurement of an object
Estimation
Useful when you are in a hurry and exact numbers are not required
Estimation
how close a measurement is to the true value
Accuracy
Is comparison of a measurement to the actual or accepted value
Accuracy
how close the measurements are to each other (reproducibility)
Precision
the correct value based on reliable references or the physical quantities with fixed values
Example: density & specific heat capacity
Accepted value
the value obtained in lab experimentations
Experimental value
accepted value - exp. value Can be (+) or (-)
Error
the absolute value of the error divided by the accepted value, then multiplied by 100%
Percent error
Le Systeme International d’Unites
SI system
True or False:
All measurement systems have standards. Standards are exact quantities that everyone agrees to use as a basis of comparison.
True
Why does the rest of the world uses SI System?
The SI (International System of Units) system is the form of measurement typically used by scientists.
- Measurements are easily understood by all scientists
- Measurements are easier to convert than the English system
- There are 7 SI base units
- From these bae units, all other SI units of measurement can be derived.
- Derived units are used for measurements such as volume, density, and pressure.
SI stands for?
International System of Units
What are the commonly used physical quantities?
- Length
- Volume
- Mass
- Density
- Temperature
- Time
The SI system is based on the number _?
10
SI Unit of length
ft, m, cm
SI unit of mass
kg, g
SI unit of volume
m³, liter
SI unit of density
kg/m³
SI unit of temperature
K, C
SI unit of time
s
are exact quantities that everyone agrees to use as a basis of comparison
Standards
the distance between two points
Length
basic unit of length in the SI System
Meter
a variation of a length measurement
Area
a measurement of the amount of space something takes up
Volume
Basic unit of volume
Liter
Objects without a definite length, width or height, can use w__ d_____ to determine volume.
water displacement
a measurement of the amount of matter in an object
Mass
how much matter is in something (mass), compared to the amount of space it takes up (volume)
Density
a measure of the kinetic energy of the atoms in an object
Temperature
True or False:
The specific gravity of a substance is the density of this substance divided by the density of water, which is 1.00 g/mL.
Unitless quantity
True
A widely used technique for such conversions using the rules of algebra
Factor-label method/ unit-factor method/ Dimensional Analysis
The ratio of the mass of an object to its volume
Density
An intensive property that depends only on the composition of a substance, not the size of the sample
Density
measures the volume of an irregularly shaped object
Water Displacement Method
When mass is measured in grams, and volume in cubic centimeters, the unit of density then is?
grams per cubic centimeter (g/cm³)
True or False:
The volume of substances will change with temperature, so accurate volume-measuring devices are calibrated at a given temperature
True
For large distances, it is most appropriate to express measurements in?
km
