[Prelim] Xy Physics Flashcards
- An experimental science
- Experiments require measurements, and we generally use numbers to describe the results of measurements
Physics
- Has both a number and unit
- Ex. 3 feet, 45 minutes, 25 degrees celsius, 1 liter, and 115 pounds
Measurement
- Any number that is used to describe a physical phenomenon quantitatively
- Ex. weight and height
Physical Quantity
- Define them only by describing how to measure them
- Ex. measuring a distance using a ruler and measuring a time interval using a stopwatch
Operational Definition
-Do not depend upon any other quantity
-only three fundamental quantities were considered: length, mass, and time. With the development of science four more physical quantities were added: temperature, electric current, luminous intensity, and amount of a substance
Fundamental (or base) Quantities
Quantities that are derived from the fundamental quantities like speed, acceleration, density, force, and momentum
Derived Quantities
- Defined as distance covered over time
- based on length and time
Speed
- Defined as mass per unit volume
- Based on mass and length
Density
Defined as mass times acceleration
Force
When we measure a quantity, we always compare it with a reference standard
Standard
- The known quantity which is used in measurement
- Ex. meter is a unit of distance, and seconds is a unit of time
Unit
Foot length, cubit, handspan, arm span, etc.
Informal system of measurement
Standardized across the world
System of measurement
- The preferred method of measurement in physics
- Has a base unit for every measurement
Metric System
The US follows the imperial system of units, also called the U.S customary units
BRITISH IMPERIAL SYSTEM / IMPERIAL SYSTEM
Inch, feet, yards, and miles
Length
Ounces (H o2), cups, pints, quarts, and gallons
Volume
Ounces (o2), pounds (lb), and tons (ton)
Mass
Measured in seconds
Time and date
- The distance between two points
- The SI unit for length is meter (m)
Length or Distance
Like a ruler, except it is 1 meter long
Meter stick
To measure long distances
Trundle wheel
For measuring distances that would be hard to measure using a meterstick or trundle wheel
Tape measure
Defined as a measuring device that is used for the measurement of linear dimensions
Vernier Caliper
- The period between events or how long it lasted
- SI unit is seconds
- Hours, days, months, and years
Time
- The amount of matter in a liquid, solid, or gas.
- SI unit for mass is gram (g)
Mass
Just put the object on the pan and read the mass
ELECTRONIC BALANCE
This compares the weight of objects in pans on each side of a balance
Double pan balance
Works like a double pan balance but instead of having a pan on each side of the balance, there is a pan on one side and three beams each with sliding weights
Triple beam balance
- The force exerted by a mass
- SI unit for force is Newtons (N)
Weight
The amount of space something occupies
Volume
A cylinder marked on the outside to indicate how much fluid it contains
Graduated cylinder
To figure out the volume of a rectangular
Volume of solids
The best way to measure the volume of an irregular solid is to place it in water and find the volume of water it displaces
Volume of irregular solids
- How hot or cold something is
- SI unit for temperature is kelvin (K)
Temperature
Used to measure temperature
Thermometer
The measure of how close the measured value is to the actual value of the quantity
Accuracy
Refers to how close measurements of the same item are to each other
Precision
- The difference between a measured quantity and its true value
- Includes random error and systematic error
Measurement Error (observational error)
Caused by a mis-calibrated instrument that affects all measurements
Systematic Error
Naturally occurring errors that are to be expected with any experiments
Random error
The difference between a measured value and a known value expressed as a percentage
Percent error
Known to be true and can be found in a standard reference
Accepted value
The value that you actually measured
Experimental Value
estimates how repeated measurements taken on the same instrument are estimated around the true score
STANDARD ERROR OF MEASUREMENT (SEM)
a measure of the variability of a distribution of repeated scores or measurements
COEFFICIENT OF VARIATION (CV)
gives an estimate of the interval where a proportion of the differences lie between measurements
LIMITS OF AGREEMENT (LOA)
- Called the error
- Indicates the maximum difference there is likely to be between the measured
value and the true value - Uncertainty is indicated by significant figures in the measured value
UNCERTAINTY
- Numbers reported in a measurement
- All of the known figures plus one estimated digit
Significant Figures
- The number that provides the most exact measurement possible
- Ex. in a thermometer, it appears that the lines are set to be 2 digits apart. The
temperature can be read between 138 and 140 degrees. Because you can’t be sure of the exact temperature, you will need to estimate the answer to 139 degrees.
Significant Digit
A rough guess of the measurement using observation and reasoning
Estimation
Picking the closest number to the specified place value based on the accuracy of
the equipment
Rounding
The total number of significant figures in the final reported value can be no more than the significant figures in the least accurate measurement. In other words, the calculated answer can be no more accurate than the measurement made by the least accurate piece of lab equipment.
Different Accuracies
A mathematical method used to convert actual measured units into the units needed for the answer to a problem
Dimensional Analysis
The relationship between the two units
Conversion Factors
A conversion factor
Ratio
Physical Quantities:
-Fundamental (or base) Quantities
-Derived Quantities
Fundamental Quantities:
-Length
-Mass
-Time
-Temperature
-Electric Current
-Luminous intensity
-Amount of substance
Derived Quantities:
Speed
Density
Force
Informal System of mesurement:
-handspan
-cubit
-armspan
-pace
-footspan
System of measurement:
-British (imperial) system or imperial system
-Metric or international system (SI)
British imperial system:
-length
-volume
-mass
-time and date
Types of measurement:
-length or distance
-time
-mass
-weight
Measurement for length or distance:
Meterstick
trundle wheel
tape measure
vernier caliper
Measurement for mass:
-electronic balance
-double pan balance
-triple beam balance
measurement for volume:
-graduated cylinder
-volume of solids
-volume of irregular solids
measurement for temperature:
Thermometer
Measurement error:
random error
systematic error
Percent error:
Accepted value
experimental value
Statistical procedures to assess measurement error:
-Standard error of measurement (SEM)
-Coefficient of variation (CV)
-Limits of agreement (LOA)
SI unit of length (distance)
meter (m)
SI unit of mass
gram (g)
SI unit of weight (or force)
newton (N)
SI unit of volume (capacity)
liter (L) or cubic meter (m3)
SI unit of temperature
kelvin (k)
SI unit of time
seconds (s)
SI unit of pressure
Newtons per square (N/m2) (pascal)
SI unit of electric current
Ampere (A)
SI unit of amount of substrate
Mole (mol)
