# The Oil Rig

### Model Description

This training aid demonstrates the kinematics of multiple connected rigid bodies in translation, rotation, or general planar motion.  This demonstration should take 10-15 minutes.

### Engineering Principle

This training aid demonstrates the kinematics of a multi-body structure.  Motion for each part of the structure is classified and discussed.  A KNEX motor brings the training aid to life.  With the oil rig in motion, students readily classify the motion of each part of the structure.  A discussion of point and body properties and their interaction across the structure becomes a natural extension of member classification.  Given the angular velocity of the motor, vector equations are then utilized to find the acceleration of the oil piston.

$v_b = v_a + v_{b/a}$

$a_b = a_a + a_{b/a}$

### What You Need

Item Quantity Description/Clarification
Oil Rig 1 Made of KNEX, a truss holds the main arm and a box frame holds the motor.  The rig is scalable.
Foam Board 1 This is used to make the main arm.
KNEX Motor 1 This provides the rotation.

### How It’s Done

Before Class: Prepare the beam with the lines drawn on it.

In Class: Typically, the training aid is hidden until the problem is developed and motion is classified.  The motor turns in both directions and at multiple speeds which allows the opportunity to get the direction “wrong” (in comparison with the figure on the board) at first and the fast setting is quite humorous to watch.

Additional Application: Trivia – Did you know?  Oil rigs don’t “suck” oil out of the ground but develop pressure into the ground which “pushes” the oil out.

### Cite this work as:

Tom Messervey (2019), "The Oil Rig," https://www.handsonmechanics.org/dynamics/592.