dcbwhaley wrote:
Steve wrote:
Your system was incomplete.
The system is what I choose it to be, so is is complete.
How can you choose to have a “complete” system which is affected by an external influence?
dcbwhaley wrote:
If I find it more convenient to use a system which transfers momentum outwards because an external force is acting, rather than a larger system which conserves momentum in the absence of an external force, that I can do so.
Yes you can, but momentum is still conserved,
just as much as energy is. This is where your argument outright fails.
dcbwhaley wrote:
I can claim that Moon is made of Cheddar cheese if I want to. But by not including the ground in my system then it is a non conserving system.
But by not including where the thermal energy of the brake is going, then it is a doubly non-conserving system (energy and momentum). True or false?
How in your system do you keep the ground from accelerating if there is a force acting upon it? If you choose to ignore additional momentum of the ground, haven't you also ignored F=ma? Now I know I don't need to strawman by asking you if f=ma is always true - do I?
dcbwhaley wrote:
Quote:
Using your same logic, I can also show how energy isn’t conserved: the vehicle is solar powered and uses a light bulb to dissipate the transferred kinetic energy.
If that is the most convenient model for you them feel free to do so. I won't argue with you.
So it is true, that for your example where you said energy is always conserved, I have shown that energy isn’t conserved?
Remember that you didn’t define your system within your original claim, hence making any such claim, let alone claiming one is true and the other false, is not reasonable.
dcbwhaley wrote:
That does not insist the momentum of a closed system remains constant.
dictionary.com wrote:
A principle stating that the total linear momentum of an isolated system remains constant regardless of changes within the system.
wiki wrote:
In an isolated system (one where external forces are absent) the total momentum will be constant
You presed the quote button instead of edit