The discussion revolves around identifying the reference frame in which an object undergoing a perfectly inelastic collision experiences no change in its kinetic energy. Participants explore various scenarios and frames of reference, including the center of mass frame and other potential frames, while addressing the implications of initial velocities and the nature of the collision.
Participants express differing views on the applicability of the center of mass frame and the relevance of initial conditions. There is no consensus on a single approach, and multiple competing views remain regarding the identification of the appropriate reference frame.
Some limitations arise from the ambiguity in the problem's formulation and the assumptions regarding the nature of the collision and the initial conditions of the objects involved.
Halfway (or rather half-speed) between initial and final rest frame (which in this case is the common center of mass frame).Raungar said:How would one find the reference frame in which an object [which undergoes a perfectly inelastic collision with a second object] experiences no change in its kinetic energy?
A.T. is exactly correct. Your "suppose..." scenario is not relevant for this problem. You have to consider all reference frames and select the one which fits the problem's requirements. A.T. told you how to select it.Raungar said:Alright, but suppose the first object starts at a constant velocity and the second at rest; without an initial frame at which both are at rest, the conjecture you present ceases to be useful. So, how might your answer adapt to fit the aforementioned situation?
Oops, you are right. Usually this question is asked about an elastic collision.Orodruin said:Some confusion might have arisen due to AT and us reading elastic instead of inelastic.
No, I read perfectly inelastic.Orodruin said:Some confusion might have arisen due to AT and us reading elastic instead of inelastic.
That part refereed the final rest frame, not the frame of constant KE. I now see it was ambiguously formulated. It should better read:DaleSpam said:but it will most definitely not be the center of mass frame for an inelastic collision.
The OP doesn't explicitly state it must be an inertial frame, so there definitely are more options even in 1d, like the trivial rest frame of the object throughout the collision.Orodruin said:assuming 3d motion is allowed, more options exist.
A.T. said:No, I read perfectly inelastic.
That part refereed the final rest frame, not the frame of constant KE. I now see it was ambiguously formulated. It should better read:
Average velocity of initial and final rest frame (the latter being the common center of mass rest frame in this case).
Wow! I am on a roll here. First I misunderstood the OP and then twice I misunderstood your post. I think I will just quit while I am behind!A.T. said:That part refereed the final rest frame, not the frame of constant KE.