PHYSICS 182A/195L LAB REPORT - LAB 1: UNIT CONVERSIONS
Lab 1: Unit Conversions
San Diego State University
Department of Physics
Physics 182A/195L
TA:
Lab partner 1:
Lab partner 2:
Date: 9/11/20
Score:
Theory
I
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PHYSICS 182A/195L LAB REPORT - LAB 1: UNIT CONVERSIONS
Lab 1: Unit Conversions
San Diego State University
Department of Physics
Physics 182A/195L
TA:
Lab partner 1:
Lab partner 2:
Date: 9/11/20
Score:
Theory
In all of the labs that we perform in the course, we will be dealing with measurements of
physical quantities such as length, time and mass. So that we can compare different
measurements of each of these quantities, we need to decide on which units to use. Units are
constants such as feet (ft), seconds (s), and pounds (lbs) that allow us to give meaning to the
numbers we use to describe lengths, times and masses.
Dimensions
Fundamental dimensional quantities (e.g. length, time, mass) have irreducible units. In other
words, their units are not complex products or fractions of other units. These are called base
quantities. On the other hand, quantities like speed, acceleration, force, and energy have units
which are products and fractions of other quantities. These are called derived quantities. For
example,
There are even more complicated quantities, such as energy:
Any physical quantity can be written as a combination of base quantities. The base quantities
length, mass, and time, can be easily measured using basic tools such as rules, scales, and
clocks. The other more complicated things like speed and acceleration can be derived by
combining theoretical understanding and practical unit analysis.
1 Department of PhysicsUnits
In order for units to be useful for comparing different measurements, they have to be used
consistently. For example, if you are told that one candy bar has 220 Calories, and another has
920480 Joules, it’s hard to determine which has more energy. Therefore, we should convert
one of these units into the other. It turns out that 1 Joule = 0.000239006 Calories. A nice
property of units is that you can treat them just like algebraic variables:
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