Task 5 : Eureka!
"Eureka!" was the cry of enlightenment made by that famous Greek scientist ,Archimedes, when he flopped into his very full bathtub of water, and a large amount of the water spilled over onto the floor ! It inspired him to come forth with his very famous Principle "When a body is immersed in a liquid there is an apparent loss of weight, and this loss of weight is equal to the weight of liquid displaced by the body"
Task 5 will prove this.
As I have only just started this task, I would like to document the salient milestones as I go along my journey.
For the experiment, I'm going to have to put together some virtual apparatus :- a tank of water, a spring balance, a beaker to catch displaced water, a weigh scale, and a couple of bodies (of the non-human variety).
I already had a tank of water from my Buoyancy Demo. All I had to add to it was a spout to guide the overflow:
Task 5 will prove this.
As I have only just started this task, I would like to document the salient milestones as I go along my journey.
For the experiment, I'm going to have to put together some virtual apparatus :- a tank of water, a spring balance, a beaker to catch displaced water, a weigh scale, and a couple of bodies (of the non-human variety).
I already had a tank of water from my Buoyancy Demo. All I had to add to it was a spout to guide the overflow:
The Water Tank
After scouring the free 3D model sites for an electronic weigh scale, and finding nil, the only course of action was to make my own. Not too grand as far as looks, but, hey, I only want something which is functional :
The Weigh Scale
A nice shiny weighpan, a digital LCD display and a Tare button.
The Spring Balance
I also had to resort to making my own skinmesh model of a spring balance. I needed a ring by which to grasp the balance and a hook to pick up the "bodies". A moving pointer and graduated scale enable the weight to be read.Hidden away in the top part of the frame is the main component.........the spring, which will stretch in proportion to the weight applied (Hooke's Law!)
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The Glass Beaker
The "Bodies"
The rigidbodies
The skinmeshes provide the visual aspect for the apparatus. However, the real meat for the physical simulation is provided by their underlying rigidbodies and the physics engine capabilities of 3D Rad (see My Blog ) Without going into detail (and my belief that a "picture says a thousand words") here are a few pics which can explain how the hook is able to pick up a block "body"
Skinmesh version
Rigidbody version
and the big surprise......the scale involved !
Comparison with 'Andro'
I have discovered, through much trial and error, that the physics just don't work nicely at the default scale.......all sorts of random and unexpected movements of the smaller objects. So, as can be seen, the scale of all my apparatus is considerable larger than default "Andro" size!
Applying Buoyancy
Applying buoyancy forces to the blocks was a cinch, using the new Buoy Object.
Weighing the Beaker
This was the most challenging part of the whole project.......getting the weigh scale to show the correct amount of displaced water.
Feedback from the 3D Rad Community Forum indicated that the app. crashed when the blocks hit against the sides of the glass tank. I had also experienced this happening occasionally but was unable to find a ready fix at the time of the original posting. I have since discovered that by doubling the thickness of the static rigidbody tank sides, one can now bang the blocks quite happily against the sides without any application failure occuring.
Here is version 2 :
Here is version 2 :
| virtualworkbench_task5_install_v2.zip |
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