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# How do I rank this physics picture?>?

The figure below shows four situations in which a box slides to the right a distance d across a frictionless floor as a result of applied forces, one of which is shown. The magnitudes of the forces shown are identical. Rank the four cases in order of decreasing work done on the box during the displacement by the force shown. (Use only ">" or "=" symbols. Do not include any parentheses around the letters or symbols. Refer to each case by its corresponding letter only.)

would it be ADCA? or A>D>C>A? huh? :l

### 3 Answers

- ArgentLv 77 years agoFavorite Answer
Case a: The force is aligned with the motion; maximum work is done.

Case b: The force is perpendicular to the motion; zero work is done.

Case c: The force is at an intermediate angle; an intermediate amount of work is done.

Case d: The force is at an intermediate angle; an intermediate amount of work is done. The angle seems to be the same as in Case c, though oppositely directed. If the angles are indeed equal, the direction of the force (forward or backward) is irrelevant, since the x-components of the forces act equally to do work (to change the amount of kinetic energy of the box).

So, a > c = d > b.

(If the angle in Case c is slightly less than in Case d, then somewhat more work is done on the box. The ordering would be a > c > d > b.)

- 5 years ago
Case A does the most work since its vector is parallel to the distance and facing its direction.

Case C does the 2nd most since its component also faces the direction of the distance, but is shorter than Case A's x component, which is its entire vector.

Case B is a vector perpendicular to the chosen direction of the distance, so its work is zero.

Case D's x component is facing the opposite direction of that of the measured distance, so its work is zero.

A>C>B>D