Nonetheless, some combinations of given input variables (such as distance-traveled, initial velocity, and elapsed proper-time) don't yield closed-form solutions obvious to us. If you think you might find explicit solutions for some of these puzzling combinations, check out here the input combinations we don't have solutions for yet. A list under construction of example problems which could use these solutions can be found here.

If you come up with the first closed-form solutions seen (by us) for any of the (presently 10 of) 31 input combinations still in parentheses in our "remain to be found" tables here, we'll post your solution (if it is manageable), and credit you as well for sending it in.

Note: six of the 10 presently un-solved combinations involve Galilean-kinematic time-elapsed, as well as either coordinate or proper time-elapsed. These are likely to be of little practical interest, as they presume input data about time-elapsed on the clocks of an observer "following" our accelerated traveler in a "Galilean chase-plane", whose offset-speed affects chase-plane clocks so that Galileo's original constant-acceleration equations describe the traveler at any speed.

We are also interested in literature solutions to the same problems, and will cite same if they are brought to our attention.

Of course, not all triplets work. For example, any velocity variable can be trivially converted from one kinematic to the next. Some acceleration problems can thus be solved within the kinematic of choice. Using conversions *post facto*, all remaining variables can be determined once *a*_{o} and any initial/final velocity pair are in hand. If we ignore differences in the kinematic that any velocity is specified in terms of, one finds only 25 *distinct* choices possible for the three given (or independent) variables which might define a 1D constant acceleration problem.

For three of these 25 choices, no *elapsed-time* is given. Hence their inputs are either independent of kinematic (i.e. *a*_{o} & d*x*) or can be trivially converted to any kinematic (e.g. velocities *w*_{o}, *w*_{f}, *v*_{o}, *v*_{f}, *u*_{o} or *u*_{f}). One can solve *relativistic* acceleration problems like these using acceleration equations from any of the three kinematics, including the well-known (and notationally simplest) equations discovered ages ago by Galileo!

Equation *sets* for such input triplets are assigned numbers in **Table 1**. For example, equation Set **0** is the set of equations which solve for d*t* and d*x* given *a*_{o}, *v*_{o} & *v*_{f}. From any introductory physics book, or from the dressed up equations or derivations pages here, one can show that equation Set **0** is simply:

Look familiar? I hope so. The other 8 equation *sets* numbered in **Table 1** can also be determined from material in these web pages. Can determine Set **1**? Set **10**? Set **20**? Set **2**?

For each of the remaining choices for our 3 independent-variables, elapsed-time in *at least* one kinematic is given. Hence the problem may have to be worked in that given kinematic, rather than in a kinematic of choice. The 12 independent-variable triplets which include *one elapsed-time* are assigned numbers in **Table 2** below. Note that the triplet **26** (d*T*, d*x* & a velocity given) is in parentheses. That's because we haven't come up with an explicit (closed-form) solution, even though graphical and numerical methods for solving this problem are in hand. Does one exist? Perhaps the question has not yet been asked in the right place!

Thus Galileo's age-old acceleration equations (with conversions as appropriate) can be used to exactly solve 13 of the 21 "*intra*kinematic" problem types listed in **Table 1** and **Table 2**, even if the velocities are relativistic! Of the 10 "*inter*kinematic" triplets not listed there, 9 involve *two* given elapsed-times. The last involves all three. These are listed in **Table 3** and **Table 4** below. An explicit solution exists for input triplet **28** below (d*b*, d*t* & a velocity given). Otherwise this territory may be relatively uncharted! Anyone out there ready to explore?

Keep me posted about progress you make in finding closed-form solutions to acceleration problems with input triplets associated with parentheses in the Tables above. In return, I will try to keep readers of this page posted on progress that I learn of in this regard.

` (Thanks. /pf :)`