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:

Physical Activity

Any bodily movement produced by skeletal muscles that requires energy expenditure, including activities undertaken while working, playing, or doing household chores.

Heart Disease

A broad term for conditions that affect the heart's structure and function.

Muscle Endurance

The ability of a muscle or group of muscles to repeatedly exert force against resistance for an extended period of time.

Muscle Strength

The maximum amount of force that a muscle can exert against some form of resistance in a single effort.