title: Gravity simulation for a ball
body: <p>I'm implementing this game that uses gravity, but I don't know how to simulate gravity for a ball.</p>
  
  <p>I have a timer that starts right after I "drop" the ball and I have to set the vertical position of my object ball.</p>
  
  <p>The related functions are:</p>
  
  <pre><code>int ball-&gt;setVerticalPosition(int Y);
  float timer-&gt;getTime();
  </code></pre>
  
  <p>Thank you!</p>