**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