Lisa is measuring the depth of a well. She drops a ball from a height of h feet into the well and measures how long it takes the ball to hit the bottom of the well. The polynomial −16t2 + 0t + h models this situation, where 0 is the initial speed of the ball and h is the height it was dropped from. She raises her arm very high and drops the ball from a height of 6.0 feet. Her stopwatch measured a time of 3.5 seconds, how deep is the well?