HP 48G - Page 38

EQ LIB) AND THE MES
The Equation Library application ((®)EQ LB)) is ex-
actly that—an access tool that lets you browse through
the built-in equation library, examining any equation
group’s formulas, variables, units, help diagrams, etc.
And with the touch of a key, you can load the equation
group into the Multiple Equation Solver (MES).
Example: If you were to stand and fire a rifle (muzzle
velocity 500 m/s) horizontally from shoulder height
(1.5 m) along a deserted stretch of highway, how far
would it have travelled along the road in that time?
Press and be sure that the menu items
and appear with the little @'s in them,
indicating that the equations will indeed include units
and that they will be Sl units. Now use (¥)to highlight
the topic Mot 1o, and press ENTER. You'll see a
selection of the various groups of motion equations.
Note how the menu items let you examine aspects of
agroup. HighlightFrojectile Mot ion and
press forapicture.... Try ETIEl to see all the
variables involved.... Press to see the first
equation in this group (you need to be patient as the
EquationWriter presents it); use L.hi3H to see each
other in its turn. At any point, press and all
equations in this group are loaded into the MES.
Now key in the known values: (o) e (1) Ca]
(o)A J(o)CEa J(NxT)(5]0)0)Wi_]. Andsolve forthe
unknown: NXTINXT) (L5 _].... #=E27B.5_m. The
MES is smart enough to determine which equa-
tion(s) to use, based on the known value(s) you input.
Notice that in the MES—just as in the (&]SOLVE) menu
(see page 15)—to store a value, you key in the value
and press its menu key; to recalla value, you press ()
and the menu key; to calculate a value, you press (&)
and the menu key. But here in the MES, any known
value—any value you key in—goes dark (e.g. [ii_]
becomes IIEIIM) to indicate its known status. And
then, when solving for an unknown, the MES denotes
with [I's the values it has used (and displays the inter-
mediate calculations it performs in the process).
One other handy MES key: To reset all values to un-
known status, press [I.THMl; to calculate all unknowns,
press IETHMN; to recall all values, press (= IETHEN.
36 THE HP 48G/GX Pocker Guipe