﻿ MotionDesigner Reference & User Interface > Motion Laws > Flexible-Polynomial Motion-Law > Throw: Quick-Return: 1: Finite Jerk @ Start/End Motion-Law

# Throw: Quick-Return: 1: Finite Jerk @ Start/End Motion-Law

### Throw: Quick-Return - Finite Jerk

It is continuous in Position, Velocity and Acceleration

We construct this Throw segment with two Flexible Polynomial segments.

Usually, the segments have an equal duration, but this is not necessary.

Continuity at the Mid-Point

At the mid-point, the Position is at its maximum and the Velocity is zero.

At the mid-point, Acceleration is finite and negative.

At the mid-point, Jerk is continuous and zero.

Position, Velocity, Acceleration, and Jerk are Continuous at the Mid-Point.

The Throw Motion-Law is Quick-Return because it has a negative acceleration at its maximum displacement. Quick-Return Start: Rise Segment 1 @ Start •Position = 0 •Zero Velocity •Zero Acceleration •Unspecified Jerk -  Actual = 320mm/s/s/s Mid-Point: Segment 1 @ End = Segment 2 @ Start •Position = 1 •Zero Velocity •Match, Do not specify Acceleration, Actual = 26.666mm/s/s •Zero Jerk End: Segment 2 @ End •Position 2 = 0 •Zero Velocity •Zero Acceleration •Unspecified Jerk  - Actual = –320mm/s/s/s Start: •Position = 0 •Zero Velocity •Zero Acceleration •Unspecified Jerk - Actual = 40mm/s/s End: •Position = 1 •Zero Velocity •Unspecified Acceleration •Zero Jerk Cv = 1.733 Ca = 4.583 Cd = –6.666 Cj max = 40 Cj min  = –22.5 Jerk at Crossover = -21.5