Re: need help finding a formula for my calc

opticsmith wrote:
[snip]
1 kg = 2.205 lb
divide by the right hand side, you get
1 kg/(2.205 lb) = 1
You can multiply any formula by this 1 and not create an error. For
example, suppose you know you weigh 220 lbs. You have
MyWeight = 220.5 lb
multiply by 1:
MyWeight*1 = (220.5 lb)*(1 kg/2.205 lb) = 100 lb*kg/lb; cancel the lb
and you get
MyWeight = 100 kg.
Easy, no? You just have to choose the right form of "1". For example,
given MyWeight in lb, you would use 1 = (2.205 lb)/1 kg instead.
Hope this helps. Good luck.
P.S. Please sign your notes in the future. We don't like anonymous
posts, much. Not your whole name and address, just a useful handle.
Irl
On Mar 24, 9:03 am, gotu...@xxxxxxx wrote:
Let's say you have a ball (shpere) that weighs 10 pounds the
material is brass which have a density of .305 cubic feet. this is all
the information I have. How can I find the diameter of the ball. I
would like to program the formula on my hp50. thank in advance

[Assuming that enough time has gone by now that any assignment is late, if indeed it is an assignment.]

You don't need all the unit conversion stuff if you simply want answers in the same units as the original input values.

So:

1) From Google or a textbook, find that the formula for the volume of a sphere is
v = 4/3*pi*r^3

2) Enter this into the 50G as an algebraic expression:
'v=4/3*pi*r^3'
where pi is the symbol for Pi (left-shift space), and leave it on the stack.

3) We also know that the density of the brass material of the sphere is
1lb = 0.305 cubic feet

4) So tell the calculator about this by entering the following equation and leaving it on the stack:
'v/0.305=10'

5) Now we've got two equations so we use the multiple equation solver. This expects to find the equations stored as a list in the special variable EQ. So first put them into a list by entering
{ }
onto the stack. And then press + twice

6) You should now have
{ 'V=4/3*pi*r^2' '.305*v=10' }
on the stack. Store in EQ by executing the STEQ command.

7) The multiple equation solver needs flag -117 (Soft MENU) set, so do that in the MODES FLAGS menu.

8) Now press APPS, choose Equation Library and then press the MES menu key. This displays the Multiple Equation Solver menu.

9) Press MINIT to initialise.

10) Press MSOLV to start the equation solver.

11) You should see R & V displayed black on white as the first two menu keys.

12) Press left-shift R and you'll see the display flash up "Solving for V", then "Solving for R" and then you'll see:
R:.853307602597

This is the radius (in feet) of a brass sphere that weighs 10lbs.

13) If you press right-shift V then you will see 3.05000000001 which is the volume (in cubic feet) of 10lbs of brass.

HTH

Of course this is all "magic" in that the calculator does everything for you. You might want to do the substitution for yourself on paper so that you can see what is happening.

Regards,

--
Bruce Horrocks
Surrey
England
(bruce at scorecrow dot com)
.