Not quite right just yet.ruggerodk wrote:
Oh, I see...;-) Thanks
So the Force N of Cf-Mass (13.333142 N) is actually 'spent' on two things:
1) preventing or holding against the Lift-mass from falling (9.806650 N)
2) lifting the Lift-mass (Net 0.030643 joules)
Is that a fair interpretation?
Or am I just delusional because I have a hard time believing that this Cf force vanish into thin air...?
N.B. - whilst the sim is presented as 2D it operates exactly as the s'Gravesande 3D experiment would with a horizontal spinning disk & gravity force - in the sim the gravity force is turned OFF so all objects experience No innate gravity force - all objects with mass still have inertia however - since it is a 2D representation I needed to simulate the effect of gravity on the lift-mass & the drive-mass, & to do that I added a vertical force downwards using gravity's acceleration of 9.80665 m/s^2 - when this is multiplied by the mass in Kg's we get the gravity force [m x a = 'g'] which you see as the red downward arrows & which appears in the 'Forces Output' - they change accordingly if you change the mass of these objects.
A force is just something that pushes or pulls an object - inertia is innate to objects with mass.
Let's do a STEP Analysis to see what's happening - I'll use two different scenario's to illustrate the points.
Simple Scenario One.
The lift-mass is disconnected from the system & calculations by removing the rope pulley connecting the Cf-mass to the lift-mass down thru the axle.
Now we only have the drive-mass being accelerated by gravity force - the drive-mass cannot fall at the same rate as the same mass in free-fall conditions because it has a job to do - that is, rotate the mass-less disk with the 1 kg sliding Cf-mass attached to it - since the Cf-mass does have inertia it will resist being sped up by the drive-mass falling & pulling it - the Cf-mass will acquire velocity & KET directly proportional to the reduction in the KET the drive-mass would have achieved if it were able to free-fall - the Cf-mass cannot have greater KET than that lost by the drive-mass - this is CoE.
Since there is NO Cpf constraint the Cf-mass will immediately begin to increase radius as it gains velocity because it's inertia causes it to want to take the path of least resistance [it doesn't like being made to turn [accelerate] in tight circles by the sides of the slot] - at no time will the KET of the Cf-mass exceed the amount of KET lost by the drive-mass [CoE].
N.B.1. since the drive-mass is the source of Input Energy to get the system rotating we can know the Gross predicted amount of Energy available from the drive-mass by calculating the PE lost [KET = mgh] - the difference between the actual KET & velocity is proportional to the velocity & KET of the Cf-mass.
N.B.2. if the drive mass were to impact a platform at any point so that it immediately stopped it's downward movement then there would be no more acceleration of the system - ques. what would happen to the Cf-mass ? - ans. actually it would continue to gain velocity as it gained radius - this is due to geometry & inertia of the Cf-mass & the disk flywheel i.e. the Cf-mass moves off tangential to the radius & if the proportion of Angular Momentum [inertia] of the disk is closer to the momentum [inertia] of the Cf-mass then the disk will loose speed & give up some of its momentum to the Cf-mass causing its velocity to increase as it spiral transited to the rim - overall energy is still conserved between the disk & the Cf-mass - if the momentum of the flywheel disk is very low in comparison to the Cf-mass then the Cf-mass will gain little extra velocity because the inertia of the disk does not 'push' the tangential movement of the Cf-mass so much - IOW's, the disk has little momentum to give up to the Cf-mass & you would see the disk almost come to a stop while the Cf-mass transited in an almost straight line to the rim - again, overall energy is conserved between the disk & the Cf-mass.
Scenario Two
This time we add back the load-mass into the system & calcs by adding the pulley-rope Cp constraint - now the Cf-mass cannot increase radius without raising the load-mass - but, the load mass has inertia & is being held down by gravity force of 9.80665 N's - so, as the drive-mass rotates the disk the Cpf increases seen as a rise in the rope tension force - when the Cpf in the rope is 9.80665 N's the gravity force of the load is in equilibrium with the Cpf of the tension forces in the pulley-rope - however, as the velocity of the Cf-mass increases further the Cf is greater than the gravity force on the load-mass & they are no longer in equilibrium - the greater force wins out & the Cf-mass moves tangentially & at the same time raises up the load-mass - what is really happening here is that the Cf-mass has inertia as momentum & its inertia overcomes the inertia of the load-mass because its being continually accelerated by the falling drive-mass giving up its PEG.
If the drive-mass were to stop then the load-mass would immediately begin a reversal process & lower down to its platform & the Cf-mass would come to a closer radius again - that is because it takes continued input of energy to make the Cf-mass move outwards AND also raise up the load-mass - at all times, whenever a system energy budget snap shot is taken, CoE is never violated.
