A Boy Pulls a Wooden Box Along a Rough Horizontal

question 58

Multiple Choice

A boy pulls a wooden box along a rough horizontal floor at constant speed by means of a force as shown.In the diagram f is the magnitude of the force of friction, N is the magnitude of the normal force, and F_g is the magnitude of the force of gravity.Which of the following must be true?

• A)P = f and N = F_g
• B)P = f and N > F_g
• C)P > f and N < F_g
• D)P > f and N = F_g
• E)none of these

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Definitions:

Trichromatic Theory

A theory of color vision that suggests our eyes can perceive color because they can detect three different wavelengths of light corresponding to red, green, and blue.

Helmholtz

A German physicist and physician known for his contributions to the understanding of the mechanisms of vision and hearing among other areas.

Color Vision

The ability of organisms to differentiate colors, achieved through the varying sensitivities of photoreceptor cells in the eyes.

Opponent-Process Theory

The theory of color vision suggesting that three kinds of cells respond by increasing or decreasing their rate of firing when different colors are present.