Skip to 0 minutes and 10 secondsNow that we can draw free-body diagrams of rigid objects - not just particles - things have become more realistic. To make this happen, we needed to introduce twisting effects. There are obvious twisting effects, like using a spanner to turn a nut or the twisting effect of a motor, which is known as torque. But less obviously, we can consider twisting effects anywhere on a rigid object by using our free-body diagram. If the object is in equilibrium, the total twisting effect everywhere on a rigid object must be zero. That gives us an extra equation. This way, we get equations for calculating forces. It's a magic moment. In time, you will absorb it into your engineer's world view.

Skip to 1 minute and 7 secondsThe equations come in various forms. With this, you can analyse practical situations, but can you specify the loads? To date, we have assumed that we know where gravity loads come from and where they are applied. Next week we'll learn more about gravity loads, and in the following weeks, we'll learn how to include friction loads on our free-body diagrams. After that, we'll talk about rolling resistance and wind loads. These are important steps towards gaining engineers' eyes.

Through Engineers' Eyes

You are on your way towards gaining Engineers’ Eyes.

This short video explains what you have encountered and what is to come.

Talking points

  • How are you getting on with the course so far?
  • What are the main things that you need to find unknown forces on a rigid body?

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