Rotational Motion
Angular Quantities
l = Rθ
Vector Nature of Angular Quantities
angular velocity direction given by the right-hand rule
Constant Angular Acceleration
Torque
force is needed for an object to rotate
Level arm is the perpendicular distance of rotation to the line along which the force acts
Rotational Dynamics
τ = RF
Rotational inertia depends on mass distribution and axis of rotation
Determining moments of Inertia
For parallel axis :
Perpendicular axis theorem(flat object) :
Rotational Kinetic Energy
Both rotational and translational kinetic energy should be count if conservation of energy is used
Rolling
Rotational + Translational = Rolling
Why does a rolling sphere slow down?
the bottom of sphere will deform
normal force create a torque that slows down sphere
Low Jing Ning A20SC0126