Fundamental Units:
Units that are basic like meters, seconds, and kg

Derived Units:
Units that are made up of multiple fundamental units like velocity which is m/s

Dimensional Analysis:
Looking at what dimensions aka [length], [time], [mass] are in an equation, and see if they are all the same or cancel out.

Scalars:
Just a number.
Time, mass, energy work, power, temp, pressure.

Vectors:
A number with a direction.
Displacement, velocity, acc, force, momentum, torque.

Significant-Figures:
Numbers that matter, AKA anything that can’t be removed in scientific notation.

Addition and Subtraction:
The answer will have the same amount of decimals as the number with the LOWEST amount of decimals.
2.347 + 1.56 = 3.907 = 3.91

Multiplication and Division:
The answer will have the same amount of sig-figs as the number with the LOWEST amount of sig-figs
2.347 * 1.56 = 3.66132 = 3.66
(Conversion factors NEVER change num of sig-figs)

Accuracy:
How close the measured values are to the TRUE value

Precision:
How close are the measured values to each other, like are they all similar, or are they very different.
ALSO how reproducible it is.

Systemic Error:
The instrument is miscalibrated or the entire experiment is just wrong

Noise Error:
You get the right answer, but each measured value is completely different.

Absolute Uncertainty:
The plain uncertainty that you get is like “dA = 0.1 m”.
This can be good for some things, but not for others, like 0.1m is good for the height of skyscrapers, but NOT for surgery.

Relative Uncertainty (percentage):
The relative percentage of what the measurement is, like how much does it stray from the actual value.
Low = Good
High = Bad

The First Condition for Equilibrium:
The net external forces on the SYSTEM must be 0, so both in x and y directions.

Static Equilibrium:
Something where there is NO motion

Dynamic Equilibrium:
Something where the velocity of the system is CONSTANT, AKA just moved by inertia

The Second Condition for Equilibrium:
There must be NO change in rotational motion, so either NO motion or CONSTANT motion.
This means that the net TORQUE is 0