A homeowner is trying to move a stubborn rock from his yard which has a mass of 1275 kg. By using a lever arm (a piece of wooden board) and a fulcrum (or pivot point) the homeowner will have a better chance of moving the rock. The homeowner places the fulcrum 29.9 cm from the rock so that it fits under the rock's center of weight. If the homeowner can apply a maximum force of 616.0 N, what is the minimum total length of board required to move the rock?

Set the moments about the fulcrum = 0; this will be the weight that balances the person's ability to apply force:


\Sigma M = 0 = 1275kg \times \ g \ \times \ 29.9 cm - 616N\ \times \ d


This gives d in centimeters for the distance from the fulcrum to the point where the 616N force is applied.