XUVAT – it’s not just a good idea, it’s a rule!

So you have learnt your 5 equations of motions, but do you really understand them? Most of you are probably nodding your heads… and those of you who aren’t should be working towards making sure you can be nodding! (please note that sometimes these are called the SUVAT or DUVAT equations as well)

You might be surprised, then, to discover that what you have learnt is only the very basics of the “Kinematics Equations”. There is much more for you to learn as you go through physics and Mathematical Methods. Let’s review some of the basics.

First and most important these equations are the “Constant (or uniform) Acceleration Equations”. This means that they only work if the acceleration of the body is constant. This means that you cannot use them if the object is increasing or decreasing it’s acceleration, i.e. it has non-zero jerk.

Secondly, you have to be careful to use the scalar version when dealing with scalars, and vector version when working with vectors – but remember that adding and subtracting vectors has special rules.

Finally, remember to use your DATA BLOCKS. Data blocks are essential to make sure you don’t make simple mistakes – and they help you earn marks in assessment (tests, exams and assignments). Speaking of which, here is the test for redoing – make sure you show a data block every time you have to use one of the XUVAT equations.

We know where some of the equations come from, and I’ve shown you one of the more complex ones. Here is a video that explains the rest:

So where to from here? You need to understand the relationship between each of the kinematics graphs (x against t, v against t and a against t), and also how they relate to the XUVAT equations. In order to do this, I want you to work completely through these two sites (this is not a work requirement, but if you are thinking that doesn’t mean you have to do it, you are absolutely wrong – and I will be able to tell.) (Yes, that is a threat… or a hint) (Hey what was that? Behind you! Something captured my attention!)

Link 1: Kinematics Equations at the Physics Classroom

Link 2: Kinematics Equations at the PhysicsLAB site

And here are two links to java applets that will allow you to investtigate some of the interactions between speed-time and distance-time graphs (1,2)

And last of all, some music to help you relax:

See you in class!

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