What is the linear velocity?

There are usually three ways to express the speed of rotation. They are rpm, angular velocity and linear velocity.  

rpm is the number of revolutions per unit time. The unit of rpm is rev/min.  

Many people confuse linear velocity with angular velocity.  I will explain the difference between linear velocity and angular velocity, and how to calculate linear velocity.
Angular velocity is the angle of rotation per unit time.  The unit of angular velocity is rad/s.  Linear velocity is the distance traveled per unit time.  The unit of linear velocity is m/s.

The formula of angular velocity(ω) is belows:
ω=θ/t (θ : angle, t : time)

Linear velocity is the distance of the arc that moves per unit time.
The length of the arc is as follows:
ℓ=rθ
The linear velocity(V) is as follows:
V=ℓ/t=rθ/t=rω
Linear velocity(V) is proportional to rotation radius(r) and angular velocity(ω).


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