AP Physics Unit 0

Physics

the study of motion, energy, and the interactions between them

MKS SI, and other variables

• MKS = meters, kilograms, seconds

• SI = international system

• mass, m, kg

• time, t, s

• speed/velocity, v, m/s

• force, F, N (newtons that are derived, kgm/s²)

• energy, E, U, K, Q, W, J (joule, kgm²/s²)

Conversion Factor

a ratio of units that is equal to one

y = mx+b

• y = dependent variable

• x = independent variable

• m = slope, change in y over change in x, rise over run

• b = y-intercept

• example: xf = vt + xi

Quadratic Function

• y = ax² + bx + c

• x = -b+-sqrtb²-4ac/2a

• example: x = xi + vit - 1/2gt²

• -1/2gt² + vit - deltax = 0

• a = -1/2g, b = vi, c = -deltax

Right Triangle

• hypotenuse = r

• vertical leg = y

• horizontal leg = x

• lower angle = theta

Common Trigonometric Functions

• sin theta = y/r

• cos theta = x/r

• tan = y/r

Inverse Functions

• theta = sin^-1 (y/r)

• theta = cos^-1 (x/r)

• theta = tan^-1 (y/x)

Pythagorean Theorem

• c² = a² + b²

• r² = x² + y²

Law of Sines

• A/sin of alpha = B/sin of beta = C/sin of gamma

Law of Cosines

• C² = A² + B² - 2ABcosgamma

Scalar Quantity

has magnitude only and is simply a value or a number

Magnitude

a number that tells us the value

Vector

a physical quantity that has both magnitude and direction

Direction

tells us which way it is pointing in our frame of reference

Starting Point & End Point

• starting point = tail

• end point = tip

Vector Sum

adding or subtracting vectors

Resultant

the result of any vector sum

Vector Notation

uses unit vectors i, j, k to define the dimensional components of a vector

Unit Vector

a vector of 1 unit value in each dimension as depicted in the xy plane

The GUESS Method

• Givens

• Unknown

• List all the givens and unknowns with variables, values, and units

• Equation

• List all the equations that include your givens and unknown

• Simplify

• Simplify the problem by modifying the equations

• Solution

• Box a solution that is solved for the unknown variable of interest