/* -------------------------------------------------------------------------   
**   Figure 11.7 Improving the workmaster.
**   Figure 6.13 The work() and drop() functions.
** -------------------------------------------------------------------------   
*/
#include "tools.h"      /* #include commands and user #defined utilities */ 

void work( void );      /* function prototypes. */
void title( void );      
double drop( double height );  

void main( void )                                                                                                              
{  
    char more;              /* repeat-or-stop switch */ 
 
    banner();                                       
    title();

    do { work();
         printf( "\n Do you want to continue (Y/N)? : " ); 
         scanf( " %c", &more );
         more = toupper(more);              
    } while ( more != 'N' );

    bye();            
} 

/* ----------------------------------------------------------------- */
void  title( void )          
{   
    puts( " Calculate the time it would take for a grapefruit\n"
            " to fall from a helicopter at a given height.\n" );    
} 

/* ------------------------------------------------------------------------   
** Perform one gravity calculation and print the results.   
*/  
void  work( void )          
{  
    double h;                /* height of fall (m) */             
    double t;                /* time of fall (s) */                
    double v;                /* terminal velocity (m/s) */  
 
    printf (" Enter height of helicopter (meters):  " );           
    scanf( "%lg", &h );                        

    t = drop( h );          /* calculate duration of fall.  */      
    v = GRAVITY * t;        /* velocity of grapefruit at impact  */  
    printf( "    Time of fall = %g seconds\n", t );                   
    printf( "    Velocity of the object = %g m/s\n", v ); 
} 

/* ------------------------------------------------------------------------   
** Calculate time of fall from a given height.   
*/ 
double 
drop (double height)      
{   
    if (height < 0) return 0;             
    else return sqrt( 2 * height / GRAVITY ); 
}