Topic 1 Flashcards
(51 cards)
Define physical quantity
A quantity that can be measured and consists of a magnitude and a unit
What are SI units?
The International System of Units
Name the 6 SI units
- Metre
- Kilogram
- Second
- Ampere
- Kelvin
- Mole
Define base quantity
Quantities on the basis of which other quantities are expresses
Define derived quantities
Quantities that are expressed in terms of base quantities
Define homogenuous
Quantities on both sides of an equation have the same unit
Homogeneous equation may not be ______ correct but a _______ correct equation is definitely homogeneous
Physically
What are the 9 prefixes, their abbreviations and powers
nano n 10^-9
micro μ 10^-6
milli m 10^-3
centi c 10^-2
deci d 10^-1
kilo k 10^3
mega M 10^6
giga G 10^9
tera T 10^12
Define scalar quantity
Quantities that have magnitude only and no direction
Define vector quantity
Quantities that have both magnitude and direction
Give 7 examples of a scalar quantity
Mass, temperature, energy, distance, speed, density, pressure
Give 6 examples of a vector quantity
Displacement, velocity, weight, acceleration, force, momentum
What is the difference between collinear and coplanar?
Collinear is parallel to the same line and coplanar is parallel to the same plane
Define uncertainty
Estimate of the difference between the reading and the true value of the quantity
Define error
A reason that a measurement might be wrong
Define precision
The smallest change in a value that can be measured by an instrument or an operator. To be precise, repeated measurements of the same thing should be close
Define accuracy
An accurate value of a a measured quantity is one that is close to the true value of the quantity
What is a systematic error?
A factor that causes readings to be different form the true value by a consistent amount each time the reading is made
What is a zero error?
A type of systematic error which occurs when an instrument gives a non-zero reading when the true value of the quantity is 0
How can you get rid of a zero error?
Can be removed by adding or subtracting it from your values
What is a random error?
Causes readings to vary around the mean value in an unpredictable way from one reading to another
How can a random error be reduced?
By repeating and averaging results
How do you find the uncertainty of a single measurement?
Precision of the measurement device (smallest value measured by the device)
How do you find the uncertainty of repeated measurements?
Half the range of the measured values
