Work Done by Variable Forces: in the Figure, Two Identical

question 14

Multiple Choice

Work done by variable forces: In the figure, two identical springs have unstretched lengths of 0.25 m and spring constants of 300 N/m. The springs are attached to a small cube and stretched to a length L of 0.36 m as in Figure A. An external force P pulls the cube a distance D = 0.020 m to the right and holds it there. (See Figure B.) The work done by the external force P in pulling the cube 0.020 m is closest to

• A) 0.12 J.
• B) 0.060 J.
• C) 6.0 J.
• D) 12 J.
• E) 0.80 J.