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This content is taken from the UNSW Sydney's online course, Through Engineers' Eyes: Engineering Mechanics by Experiment, Analysis and Design. Join the course to learn more.

Skip to 0 minutes and 10 seconds We aim to help you develop engineers’ eyes. You’ve made a start already. You’ve seen how the physical world is represented by mathematics but with a practical purpose in mind. And you’ve seen how engineering analysis is categorised, for example, into statics and dynamics. That’s a start. But there is one vital feature you have to take into your world view as you develop engineers’ eyes. It’s the free-body diagram. You will find it in every module from now on. For example, take week six. A toy tractor being pulled along a sloping tabletop is represented by a diagram of the tractor in space with forces applied. The free-body diagram seems a simple concept, but don’t be fooled.

Skip to 1 minute and 3 seconds It’s deep and at the same time practical and mysterious. Practical, because it enables us to make calculations reliably. Mysterious, because it takes us into a parallel world where mathematical squiggles on paper somehow relate to physical reality. There’s a mystery. As Eugene P Wigner wrote, he was a Nobel prize winning physicist, “the miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift, which we neither understand nor deserve.” But this is engineering. It doesn’t do to dwell on mystery. We’ll just accept that the free-body diagram is an essential part of developing engineers’ eyes.

Through Engineers' Eyes

At the end of each week, a quick video will highlight your progress towards Engineers’ Eyes and a concept wheel will show you how it all fits in.

Wheel revealing the words Week 1 Load/extension for springs, stiffness of springs, linear/non-linear springs, static/dynamic conditions Week 1 concept wheel (Click to expand)

You haven’t heard much about forces so far. In fact we didn’t want to use the word at all (although it might have crept in by mistake somewhere). Force is a mysterious concept that we’ll explore next week.

Instead we talked about ‘loads’. Loads are a plain fact. You saw us hang a weight pan full of washers on an elastic band. That’s a load. If it was stationary it was a static load: if it was moving then it might be a dynamic load.

You heard a lot about springs. For example, we measured how a spring stretched when we added load to it. That led to the idea of stiffness.

Next week introduces load transducers - devices that can tell us how big a load is. But more importantly, you’ll start hearing about ‘forces’, and our load transducers will turn into force transducers.

Talking points

These are to get you started. Share any other thoughts you’ve had.

  • Week 2 will involve trigonometry. When did you last use sine, cosine and tangent?

Share your experiments

Don’t forget to share your experiments on the Through Engineers’ Eyes Padlet wall for this week.

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This video is from the free online course:

Through Engineers' Eyes: Engineering Mechanics by Experiment, Analysis and Design

UNSW Sydney