Circular motion

Angle in radian

arc length/ radius

Angle in radius (terms of pi)

2π r / r = 2π (whole circle)

angular velocity (a.k.a angular frequency)

ω = θ/ t (s= vt, v = θ)
(measured in rad s ^-1)

Angular velocity for 1 circle

ω = 2π/ t = 2πf

Linear speed

v = r ω

Centripetal

Towards the centre of the circle

radians to degrees

x 180/ π

degrees to radian

x π/ 180

1 radian

57 degrees

Centripetal (Defining condition)

• if the resultant force acting is perpendicular to the velocity of the object

• the resultant force acting towards the centre is the centripetal force (the velocity acts tangentially)

Energy change

• centripetal force and velocity are perpendicular = no work done

• energy of the object remains constant

• velocity constantly changes

• object accelerates towards the centre of the circle