A force-position graph shows a straight horizontal line at $F=12$ N from $x=3$ m to $x=9$ m. What method is most appropriate for finding the work done over this interval?

• A. Use a quadratic antiderivative because every force-position graph requires calculus
• B. Use a triangular area because the force changes linearly with position
• C. Use the rectangular area or equivalently $W=F\Delta x$ because the force is constant over the interval
• D. Use momentum conservation because work cannot be determined from a constant-force graph

Answer: (C)