Unit 12 Variables

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

Gravitation constant (6.67×10^-11 N*m²/kg²)

[θ]theta (motion)

angular position (rad)

[Δθ]Deltatheta

angular distance (rad)

[ω]omega

angular velocity: rate of change of angular position (rad/s)

[α]alpha

angular acceleration: rate of change of angular velocity (rad/s²)

[Δx or s]Deltax or s

arc length or circular distance (m)

[v_t] v_t

tangential velocity (m/s)

[a_t] a_t

tangential acceleration; changes the speed; points tangentially forward/backward (m/s²)

[a_c] a_c

centripetal acceleration: changes the direction ; points towards the center (m/s²)

[τ]tau

torque (N*m)

[θ]Theta (torque)

Angle between moment arm and force (Degree °)

Rotational equilibrium

Net torque = 0 => angular acceleration = 0

Translational equilibrium

Net force = 0 => acceleration = 0

Static equilibrium

Net torque and net force = 0 => no acceleration

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]DeltaL (effect)

angular impulse: change in angular momentum (kg*m²/s)

[J_rot] Jrot (cause)

angular impulse: an external torque applied for a time interval (Nm*s)

[K_rot] K_rot

rotational kinetic energy (J)

T

Period: time for one cycle (s)

f

Frequency: cycles in one second (Hz or s^-1)

Constant circular average velocity

v = [2pir/T] 2πr/T

r (gravitation)

distance between the centers of two masses (m)

m

mass (kg)