It took me quite a bit to figure out how to handle the ball's behaviour. Using print statements and studying how a ball should work, I managed to write some logic for it. I added new attributes to the ball struct and used them to manage the calculations for the ball's behavior.

Results struct

struct Results
{
    double maxHeight; // calculate max height (remove)
    double timeToMaximumHeight; // time to maximum height (remove)
    double timeToLand; // time to land (remove)
    int initialVelocity; // original text box value
    int operatedVelocity; // used for ball movement
    double gravity; // earth's gravitational force
    bool doResultsExist; // Check if the results can be applied
    bool upwardsMovement; // The ball goes up or down?
};

I used the simple but useful distance = speed * time formula to handle upwards and downwards movement. For each bounce I divide the initial velocity by 1.1 to lower the height of each bounce.

When the operated velocity reaches zero or the ball hits the ground, the ball changes direction. If the ball hits the ground, the initial velocity decreases. This behavior continues as long as the initial velocity is greater than 1. Once the initial velocity is 1 or less, the simulation ends, and the application resets.

Ball movement behavior

if(hasSimStarted)
{
    if (executionResults.operatedVelocity > 0)
    {
         if (executionResults.upwardsMovement) 
        {
            ball.y -= (double)executionResults.operatedVelocity;
            executionResults.operatedVelocity -= (int)executionResults.gravity * deltaTime;  
        }else
        {
            ball.y += (double)executionResults.operatedVelocity;
            executionResults.operatedVelocity += (int)executionResults.gravity * deltaTime; 

            if (ball.y > windowHeight - ball.radius)
            {
                executionResults.operatedVelocity = 0;
            }
    }
}else if (executionResults.operatedVelocity <= 0) 
{
    if (!executionResults.upwardsMovement && executionResults.initialVelocity > 1)
    {
        executionResults.initialVelocity = executionResults.initialVelocity / 1.1;
    }

    executionResults.upwardsMovement = !executionResults.upwardsMovement;
    executionResults.operatedVelocity = executionResults.initialVelocity;

    if (executionResults.initialVelocity <= 1)
    {
        hasSimStarted = false;
    }
}

startButton.text = "Stop";

}else
{
    ball.y = windowHeight - ball.radius;
    startButton.text = "Start";
}

GenerateBall(ball, appRenderer);

Demonstration