You are on a co-op job with a construction firm that has been contracted to build a large waterfront pier on Lake Lanier. You are on-site one afternoon while they are driving the steel footings upon which the pier will be constructed. You watch as a large pile-driving machine lifts a heavy weight to a height of 3 meters above a vertical steel I-beam that is partially embedded in the lakebed. The weight is released, falling along guide-rails to strike squarely atop the I-beam. You notice that the beam is forced down about 14 cm with each drop of the weight. At that moment your co-op supervisor walks up and, as a test, asks you to estimate the average force on the beam during such an impact. She tells you that the pile driver uses a 750 lb weight as its hammerhead. Your first guess is 750 pounds" which she replies, "Try again." What is your second response?