FIZKS

X

position [m]

v

velocity: speed and direction; rate of change of position [m/s]

Vavg

average velocity = distance interval over time interval from beginning to end [m/s]

v_A,B

velocity of object A relative to (measured by) observer B ([m/s]

Δx

displacement: final position - initial position; skip middle [m]

a

acceleration: rate of change of velocity [m/s²]

g

gravitational field strength [m/s²] or [N/kg]

Δt

time interval [s]

F

force: a push/pull interaction between exactly two objects [N]

m

mass: resistance to change in motion [kg]

μ

coefficient of friction: dependent on materials only

k (springs)

spring constant [N/m]

Δx (springs)

compression/stretch of spring from equilibrium [m]

Ff,s

static friction: happens when surfaces are trying to slide together, but arent [N]

Ff,k

kinetic friction: happens when surfaces are sliding together [N]

Fg

weight; force of gravity [N]

Fn

normal force: surface pushing back; always perpendicular to surface [N]

Ft

tension; always pulls [N]

equilibrium:

net force is zero

p

Linear momentum [kg*m/s]

Δp (effect)

Linear impulse: change in linear momentum [kg*m/s]

J (cause)

Linear impulse: an external force applied for a time interval [N*s]

Δt (momentum)

Time interval an external force is applied to change a system's momentum [s]

Xcm or x̅

position of the center of mass: the weighted-average location of the parts of the system [m]

Vcm or v̄

velocity of the center of mass: the weighted-average of the entire systems motion [m/s]

Σp

Total momentum of a system; only changed by external force [m/s]

Kt

Translational kinetic energy: energy of linear motion [J]

Ug

gravitational potential energy: energy stored in a gravitational field [J]

Us

spring potential energy: energy stored in something squished or stretched [J]

Etherm

Thermal energy [J]

ΣE

Mechanical energy of a system; changed by external work, collisions, or a heat source [J]

Δy (energy)

when calculating Ug: height change of the center of mass [m]

W (effect)

work: a change in mechanical energy [J]

W (cause)

work: a parallel force applied over a distance [J]

d (energy)

distance an external force is applied to do work [m]

F||

component of force parallel to motion: this component does work/changes the speed, but cant change the direction [N]

F⊥

component of force perpendicular to motion: this component changes the direction but cant do work/change the speed [N]

θ (work)

angle between applied force and motion for calculating work [º]

P

power: rate of change of energy/rate of work [W or J/s]

Elastic collision:

system kinetic energy is conserved

Inelastic collision:

system kinetic energy is lost/converted to another form of energy

Completely inelastic collision:

system kinetic energy is lost/converted to another form of energy AND the objects stick together

Explosion:

system kinetic energy is increased/converted from another form of energy

T

period: seconds per one cycle [s]

f

frequency: cycles per one second [Hz] or [s⁻1]

A

amplitude: max. displacement from equilibrium (m)

Restoring force:

1) Points towards equilibrium

2) Proportional to distance from equilibrium

l (pendulum)

length of pendulum [m]

ω (Harmonic motion)

Angular frequency = 2π/ period

Simple Harmonic Motion vmax shortcut:

|Vmax| = |ωA|

Simple Harmonic Motion amax shortcut:

|amax| = |ω^²A|

Ac

centripetal acceleration: changes the direction, not the speed; points towards the center [m/s²]

ΣFc

centripetal force: when the net force causes circular motion; not an actual force [N]

Fg

Weight or force of gravity [N]

g

Gravitational field strength ([N/kg] or [m/s²]

r (forces)

Distance between the centers of two masses [m]

r (orbits)

Distance from the center of the planet to the orbiting object [m]

G

Gravitational Constant (6.67x10-11) [Nm²/kg²]

θ (motion)

Angular position [rad]

Δθ

angular distance [rad]

ω

angular velocity: rate of change of angular position [rad/s]

α

angular acceleration: rate of change of angular velocity [rad/s²]

∆x or s

arc length or circular distance [m]

vt

tangential velocity [m/s]

At

tangential acceleration; changes the speed ; points tangentially forward/backward [m/s²]

τ

torque [N*m]

θ (torque)

Angle between lever arm and force [º]

Rotational equilibrium

Net torque = 0 => angular acceleration = 0

Static equilibrium

Net torque and net force = 0 => no acceleration

Translational Equilibrium

Net force = 0 => angular acceleration =0

I (rotation)

moment of inertia: resistance to CHANGE in angular motion [kg*m²]

r (rotation)

distance from pivot point to force or object [m]

L

Angular Momentum ([kg*m²/s]

ΔL (effect)

Angular impulse: change in angular momentum [kg*m²/s]

Jrot (cause)

Angular impulse: an external torque applied for a time interval [Nm*s]

Krot

rotational kinetic energy [J]

P (fluids) (definition)

Pressure: perpendicular force per unit area (definition) [Pa] or [N/m²]

P (fluids) (effect)

pressure is a scalar; fluids push “out” in all directions (effect) [Pa] or [N/m²]

Rho (fluids)

density: mass per volume [kg/m³]

h (fluids)

depth of fluid for finding pressure [m]

Fb

buoyant force; always points up [N]

V (buoyancy)

volume of displaced fluid (not volume of object) [m³]

Archimedes’ Principle

buoyant force = weight of the displaced fluid

A (fluid flow)

cross-sectional area

Av or DeltaV/t

volume flow rate [m³/s]

P (fluids only)

pressure: energy per volume [Pa] or [N/m³] or [J/m³]

1/2pv²

kinetic energy per volume [J/m³]

pgy

Potential energy per volume [J/m³]

Distance:

from initial to final position; path matters