Question

The figure above is a force vs. displacement graph, showing the amount of force applied to an object by three different people. Al applies force to the object for the first $4m$ of its displacement, Betty applies force from the $4m$ point to the $6m$ point, and Chuck applies force from the $6m$ point to the $8m$ point. Which of the three does the most work on the object?

• A. Al
• B. Betty
• C. Chuck
• D. Al and Chuck do the same amount of work
• E. Betty and Chuck do the same amount of work

Answer 1

Answer: (C)

Chuck

The work done in a $F-d$ graph is given by the area under the force curve and displacement axis .

Work done by Al =area of triangle$=\frac{1}{2}\times 4\times -4=-8J$ (-ve sign shows the direction of force)

Work done by Betty =area of triangle$=\frac{1}{2}\times 2\times 4=4J$

Work done by Chuck =area of rectangle$=4\times 2=8J$