14 The HP-15C: A Problem Solver

The time an object takes to fall to the ground (ignoring air friction) is given by the formula

t = 2h , g

where t = time in seconds, h = height in meters,

g = the acceleration due to gravity, 9.8 m/s2.

Example: Compute the time taken by a stone falling from the top of the Eiffel Tower (300.51 meters high) to the earth.

Keystrokes

Display

 

300.51 v

300.5100

Enter h.

2 *

601.0200

Calculates 2h.

9.8 ÷

61.3286

(2h) /g.

¤

7.8313

Falling time, seconds.

Programmed Solutions

Suppose you wanted to calculate falling times from various heights. The easiest way is to write a program to cover all the constant parts of a calculation and provide for entry of variable data.

Writing the Program. The program is similar to the keystroke sequence you used above. A label is useful to define the beginning of a program, and a return is useful to mark the end of a program. Also, the program must accommodate the entry of new data.

Loading the Program. You can load a program for the above problem by pressing the following keys in sequence. (The display shows information which you can ignore for now, though it will be useful later.)