Rotational or Angular Motion Angular displacement – vector  to the plane of motion + counterclockwise pts up Clockwise pts down Ex. Screwdriver or water faucet

s = r rotational vel.  = /t v = s/t = r/t = r linear velocity referred to as tangental or translational

See analogous eqns on p.305 a = r  = f - i a = v/t t  = it + ½ t2 s = vit + ½ at2 vf2 = vi2 + 2as f2 = i2 + 2

ac = v2/r = r22/r = 2r KE = ½ mv2 = ½ I2 F = ma  = I p = mv ac = v2/r = r22/r = 2r KE = ½ mv2 = ½ I2 F = ma  = I p = mv L = I F = p/t  = L/t

W = Fs = Fr =  P = W/t = /t =  = Fv See fig W = Fs = Fr =  P = W/t = /t =  = Fv See fig. Total acceleration of pt on a rotating body is equal to the vector sum of the (ac2 + atangent2)0.5 = aresult

Moment of inertia, I, resistance for a body to change rotational motion (kg.m2) See table of shapes. Inertia is unique to the shape of a body KE = ½ mv2 = ½(mr2)2 = ½ I2 (for thin ring)

Torque: 2 methods: force applied to cause a body to rotate = Fr = Fr