Engineering Design - Mobile


Design Statement

Design and construct an art mobile around a general theme using physics to demonstrate translational and rotational equilibrium


The mobile can be made of any type of material, though fragile or expensive objects are discouraged.

The mobile must have a minimum of three freely swinging horizontal arms. Strings may NOT be attached at the center of mass of a support rod. (The lightning bolt in the image is attached at the center of mass and would be a disqualifier)

Maximum limits are as follows: 100 cm wide, 100 cm deep, 100 cm tall.



1. Sketch the general plan of your mobile, this plan can be modified as you go, you will turn in a final blueprint of your finished mobile.

2. Find the mass of each element, including the rods

3. Construct your mobile, trial and error may be necessary to get the elements to hang in equilibrium. Make notes on your general plan of any modifications you have made.

4. Construct your final blueprint. Determine the position and length of each support string, include these distances on your final blueprint along with the masses of each hanging element


Additional Background Information

*Transitional Equilibrium occurs when the net force acting on an object is zero, therefore it is not moving.
**Rotational Equilibirum occurs when an object rotates around a pivot point.

This presentation may give you further information on The Concept of Equilibrium