We have looked at circular motion using the same measures as linear motion. To look at rotation in more detail, though, we need to work in rotational units - measuring the angle rotated through, the angular sped, and angular acceleration.
- Angular momentum is defined as the product of rotational inertia and angular velocity.
- Torque is defined as τ=rFsinθ, where the angle θ is the angle between the lever arm r and force F. The symbol for torque is the Greek letter tau (τ)
- By definition a counterclockwise torque is positive and a clockwise torque is negative.
- Two conditions of equilibrium:
- Translational equilibrium: ∑F=Fnet=0
- Rotational equilibrium: ∑τ=τnet=0