earth, moon. Charged particles moving in a magnetic field. Rides to car rounding a curve. Blood circulating. Further mor
Circular Motion Daw Myo Myo Naing Demonstrator Department of Physics
What ? A body is moving in a circular path Related The motion of planets and satellite the earth, moon Charged particles moving in a magnetic field Rides to car rounding a curve Blood circulating Further more related to vibrations of waves
Rotates Circular motion Revolves Rotates axis is inside the rotating body eg.the earth rotates daily about on its own axis. Revolves axis is outside the rotating body eg. the earth revolves yearly around the sun.
Angular Displacement(θ) θ=θ ̊
B
S
r
θ r
A θ=0 ̊
Δθ=θf –θi=θ 1revolution= 360 ̊=2π radian
S θ= r
Angular displacement () • The change in angular position( vector) • perpendicular to the plane of the motion
s r θ = angular displacement s = arc length(linear distance,SI unit is m) r = radius of circular path( unit is m rad-1)
• Measure of an angle • Bounded by an arc • Length is equal to radius of circle
2π rad=360 ̊=1rev
360 1 rad = = 57.3 ̊= 0.159 rev 2
• θ=1rad=57.3 ̊
Angular velocity () The time rate of change of angular displacement( vector )
Δθ θ ωave = Δt t Unit – rad s1, rev s1, deg s1, rpm,rps 1rpm= 2
60
rad s-1 ,
1rps =2π rads-1
1rads-1= ? rpm
θ • Angular velocity ω= t v3 θ2 θ1
r
r r
v2 ω
v1
Angular acceleration () The time rate of change of angular velocity
0 t t
Unit - rad s2
deg s2 rev s2
Relation between linear displacement and angular displacement S=r linear velocity and angular velocity v=rω linear acceleration and angular acceleration a=rα
Linear velocity can also
be called tangential velocity Linear acceleration can also be called tangential acceleration
• Why? a point is moving along the tangential direction at any instant
aT
vT
aT vT
vT
aT
Uniform circular Motion (ω=constant) • Motion in a circle at constant speed • Magnitude of the velocity is constant • Direction of velocity is always changing with time • Uniform circular motion is called accelerated motion
