/* ---------------------------------------------------------------------  
// Figure 5.6:  The grapefruit returns.
// Figure 5.8:  The drop() function.
// --------------------------------------------------------------------- 
// Determine the time it takes for a grapefruit to hit the ground when      
// it is dropped with no initial velocity from a helicopter hovering at  
// height h. Also determine the velocity of the fruit at impact. Use a    
// separate function to compute the time of travel of the grapefruit    
*/ 
 
#include "tools.h"                                          
  
double drop( double height );       /* Prototype declaration of drop. */ 

void main( void )                                             
{ 
    double h;       /* height of fall (m) */      
    double t;       /* time of fall (s) */            
    double v;       /* terminal velocity (m/s) */     

    banner();                                             
    puts( "\n Calculate the time it would take for a grapefruit\n"
          " to fall from a helicopter at a given height.\n" );     
    printf( " Enter height of helicopter (meters): " );             

    scanf( "%lg", &h );     /* keyboard input for height  */ 

    t = drop( h );          /* Call drop.  Send it the argument h. */
    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();                                                 
} 

/* ---------------------------------------------------------------------- */  
/* Time taken for an object dropped from height meters to hit the ground. */  
double drop ( double height )  
{    
    double time;
 
    if (height < 0)   {                   /* Exit gracefully after error. */  
        fatal( " Error: height must be >= 0.  You entered \%g", height ); 
    }                                                                
    time = sqrt( 2 * height / GRAVITY );    /* Calculate the time of fall */ 
    return time; 
}