APP1 Unit 10 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 (Nᐧm²/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)

ac

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

τ

torque (Nᐧm)

θ (torque)

angle between moment arm and force (°)

Rotational equilibrium

Net torque = 0; angular acceleration = 0

Translational equilibrium

Net force = 0; acceleration = 0

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Static equilibrium

Net torque and net force = 0; no acceleration

I (rotation)

moment of inertia: resistance to CHANGE in angular motion (kgᐧm²)

r (rotation)

distance from pivot point to force or object (m)

L

angular momentum (kgᐧm²/s)

ΔL (effect)

angular impulse: change in angular momentum (kgᐧm²/s)

Jrot (cause)

angular impulse: an external torque applied for a time interval (Nmᐧs)

Krot

rotational kinetic energy (J)

The moment of inertia of an object about an axis

I=mr²

Relating rotational and linear variables:

(1) ∆x=∆θr
(2) v=ωr
(3) a=αr