Movement Ratio

Machines and movement ratio (velocity ratio)

A machine is a device that can change the magnitude and line of action of a force.

Machines - movement ratio - distance and effort load

Examples are

  • pulley systems
  • gear systems
  • screw-jacks

A simple machine amplifies the input force (effort) to a larger output force (load).

Movement Ratio

The movement ratio (or velocity ratio) of a machine is defined as the ratio of the distance moved by the effort to the distance moved by the load. Movement ratio can be expressed as

Mr = se / sl  

   = velocity ratio                         (1)


Mr = movement ratio

se = distance moved by the effort   (m, ft)

sl = distance moved by the load     (m, ft)

Machine Efficiency

The efficiency of a simple machine is defined as the ratio of the force ratio to the movement ratio and can be expressed as

μ = Fr / Mr                       (2)


μ = machine efficiency

Fr = force ratio

Related Topics

  • Dynamics - Motion - velocity and acceleration, forces and torques
  • Mechanics - Forces, acceleration, displacement, vectors, motion, momentum, energy of objects and more

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