The coefficient of kinetic friction between a 20 kg box and the floor is 0.40. How much work do

step 1 In this video we are going to focus on finding out the amount of work done when suppose we are h

The coefficient of kinetic friction between a 20 kg box and...

The coefficient of kinetic friction between a $20 \mathrm{~kg}$ box and the floor is $0.40$. How much work does a pulling force do on the box in pulling it $8.0 \mathrm{~m}$ across the floor at constant speed? The pulling force is directed $37^{\circ}$ above the horizontal (a) $343 \mathrm{~J}$ (b) $482 \mathrm{~J}$ (c) $14.4 \mathrm{~J}$ (d) None of these

The coefficient of kinetic friction between a $20 \mathrm{~kg}$ box and the floor is $0.40$. How much work does a pulling force do on the box in pulling it $8.0 \mathrm{~m}$ across the floor at constant speed? The pulling force is directed $37^{\circ}$ above the horizontal
(a) $343 \mathrm{~J}$
(b) $482 \mathrm{~J}$
(c) $14.4 \mathrm{~J}$
(d) None of these

Key Concepts

Work (Physics Concept)

Work is defined as the dot product of force and displacement. This means that only the component of the force in the direction of displacement contributes to the work done. In problems involving forces at an angle, the force must be resolved into horizontal and vertical components, and the work done is calculated using the horizontal component when displacement is along the horizontal direction.

Kinetic Friction

Kinetic friction is the resistive force encountered when an object slides over a surface. It is calculated as the product of the coefficient of kinetic friction and the normal force. The normal force may differ from the weight if additional vertical forces are applied, and in such cases, these vertical components must be taken into account when determining the frictional force.

Vector Decomposition

When forces are applied at an angle, they must be resolved into their horizontal and vertical components using trigonometric functions. This process, known as vector decomposition, is critical for analyzing the effects of each component separately, especially when calculating the work done or the net force acting along a particular direction.

Equilibrium and Constant Speed

Constant speed indicates that the net force acting on the object in the direction of motion is zero (Newton's first law). This equilibrium condition allows for setting up a balance between the applied force component and other opposing forces, such as friction. It is essential for solving for unknown force magnitudes in problems where friction is affected by vertical components of the applied force.

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