/* ---------------------------------------------------------------------  
// Figure 5.4  Calling library functions.
// ---------------------------------------------------------------------    
*/
#include "tools.h"

void main( void )                                                
{   
    double h;                   /* height of fall (m) */       
    double t;                   /* time of fall (s) */                
    double v;                   /* terminal velocity (m/s) */ 
    
    banner();                                            
    puts( " Calculate the time it would take for a grapefruit\n" 
          " to fall from a helicopter at a given height." );  

    printf( "\n Enter height of helicopter (meters):  " );           
    scanf( "%lg", &h );         /* keyboard input for height */
 
    if (h < 0)   {              /* exit gracefully after error */  
        fatal( " Error: height must be >= 0.  You entered %g", h );              
    }                                                               
    else  {                          /* otherwise, */                   
        t = sqrt( 2 * h / GRAVITY ); /* calculate the time of the fall */ 
    }                                                                    
    v = GRAVITY*t;                   /* velocity of grapefruit at this time */  

    printf( "      Time of fall = %g seconds\n", t );                  
    printf( "      Velocity of the object = %g m/s\n", v );            
    bye();
}