/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 11 A boxed 10.0 -kg computer monito... [FREE SOLUTION] | 91Ó°ÊÓ

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A boxed 10.0 -kg computer monitor is dragged by friction 5.50 \(\mathrm{m}\) up along the moving surface of a conveyor belt inclined at an angle of \(36.9^{\circ}\) above the horizontal. If the monitor's speed is a constant 2.10 \(\mathrm{cm} / \mathrm{s}\) , how much work is done on the monitor by (a) friction, (b) gravity, and (c) the normal force of the conveyor belt?

Short Answer

Expert verified
(a) Work by friction: depends on friction coefficient, (b) Work by gravity: \(- F_{g, \text{parallel}} \times 5.5 \), (c) Work by normal force: 0.

Step by step solution

01

Calculate the gravitational force component along the incline

The force of gravity acting on the monitor can be decomposed into two components: one parallel to the incline, which is the one causing the monitor to slide down, and the other perpendicular to the incline. The parallel component is given by \( F_{g, \, ext{parallel}} = m \times g \times \sin(\theta) \), where \( m = 10.0 \, \text{kg} \) is the mass of the monitor, \( g = 9.81 \, \text{m/s}^2 \) is the acceleration due to gravity, and \( \theta = 36.9^{\circ} \). Substitute the values to find \( F_{g, \, ext{parallel}} \).
02

Calculate the work done by gravity

The work done by gravity is calculated by multiplying the gravitational force component along the incline with the distance moved along the incline: \( W_{\text{gravity}} = F_{g, \, \text{parallel}} \times d \), where \( d = 5.50 \, \text{m} \) is the distance. Use the previously calculated \( F_{g, \, \text{parallel}} \) to find \( W_{\text{gravity}} \).
03

Calculate the work done by friction

The work done by friction is given by \( W_{\text{friction}} = -F_{\text{friction}} \times d \), where \( F_{\text{friction}} = \mu \times F_{\text{normal}} \) is the frictional force. We need to find the normal force, which is the component of the gravitational force perpendicular to the incline: \( F_{\text{normal}} = m \times g \times \cos(\theta) \). Substitute these into the friction force equation to find \( W_{\text{friction}} \).
04

Calculate the work done by the normal force

The work done by the normal force is zero because the normal force acts perpendicular to the direction of motion. Thus, \( W_{\text{normal}} = 0 \).
05

Compile the results

Using the calculated values, summarize the work done by each force. The work done by gravity and friction will have numerical values, while the work done by the normal force is zero. Present each result from the previous steps.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Gravitational Force
The gravitational force plays a pivotal role when objects move along an inclined plane. This force, due to the mass of the object and Earth's gravitational pull, always acts downward towards the center of the Earth. For an object on an incline, gravitational force can be split into two components:
  • A parallel component, which pulls the object down the slope.
  • A perpendicular component, which is towards the surface of the incline.
For the 10.0-kg monitor moving up the conveyor belt, the parallel component can be calculated using the formula:\[F_{g, \text{parallel}} = m \times g \times \sin(\theta)\]where:
  • \(m\) is the mass (10.0 kg),
  • \(g\) is the gravitational acceleration (9.81 m/s\(^2\)),
  • \(\theta\) is the angle of the incline (36.9\(^{\circ}\)).
This calculation helps determine how much of the gravitational force works towards pulling the monitor back down the incline.
Frictional Force
Frictional force is the resistant force that acts opposite to the direction of motion. It's crucial for tasks like moving an object up an incline, as it determines the effort required to drag the object against this resistance. The amount of frictional force on an incline is influenced by the normal force and the coefficient of friction.The frictional force (\(F_{\text{friction}}\)) can be calculated as:\[F_{\text{friction}} = \mu \times F_{\text{normal}}\]where \(\mu\) is the coefficient of friction. The work done by friction as the monitor is moved can be calculated by multiplying this frictional force with the distance: \[W_{\text{friction}} = -F_{\text{friction}} \times d\]The negative sign indicates that friction opposes the movement. Understanding friction is key to calculating the total effort needed to slide the 10.0-kg monitor up the 5.50 m incline.
Normal Force
While it may seem that normal force would perform work when an object moves along a surface, this is usually not the case on a flat or inclined plane. The normal force acts perpendicular to the surface, which means it doesn't contribute to motion along the plane itself.For the monitor on the incline, normal force (\(F_{\text{normal}}\)) can be calculated using:\[F_{\text{normal}} = m \times g \times \cos(\theta)\]This calculation uses the cosine of the angle due to the perpendicularity relative to the surface of the incline. Importantly, because the normal force is perpendicular to the direction of motion, the work done by it is zero:\[W_{\text{normal}} = 0\]This reveals that while essential in balancing forces, the normal force doesn't contribute to the energy transfer along the motion's direction.
Inclined Plane
An inclined plane is a flat surface tilted at an angle to the horizontal. It significantly affects how forces like gravity and friction act on an object. Moving an object up an incline requires understanding these forces' components due to the angle.Key aspects include:
  • The angle of inclination affects both the component of gravitational force along the plane and the normal force.
  • It requires different calculations as opposed to movement on a horizontal surface.
The angle of 36.9\(^\circ\) for the conveyor belt is significant as it alters the force vectors on our monitor. By decomposing gravitational force into parallel and perpendicular components, you can precisely determine how the plane's tilt influences both the energy required for movement and the impact of friction.
Work Done
Work done through mechanical means on an object is calculated based on the force applied and the distance moved along the direction of that force. It is expressed in joules (J), reflecting the energy transfer to or from an object.Formally, work done (\(W\)) is defined as:\[W = F \times d \times \cos(\phi)\]where:
  • \(F\) is the magnitude of the force applied,
  • \(d\) is the distance moved by the object, and
  • \(\phi\) is the angle between the force and direction of motion.
For the 10.0-kg monitor, various forces are at play:
  • Gravity does negative work as the object is dragged upwards against it.
  • Friction also does negative work opposite to the motion.
  • The normal force doesn't contribute due to its perpendicular orientation.
In applying these principles, each force must be considered individually to determine the total work done, integrating gravitational effects, frictional resistances, and adjustments due to the incline's angle.

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Most popular questions from this chapter

A block of ice with mass 2.00 \(\mathrm{kg}\) slides 0.750 \(\mathrm{m}\) down an inclined plane that slopes downward at an angle of \(36.9^{\circ}\) below the horizontal. If the block of ice starts from rest, what is its final speed? You can ignore friction.

You are a member of an Alpine Rescue Team. You must project a box of supplies up an incline of constant slope angle \(\alpha\) so that it reaches a stranded skier who is a vertical distance \(h\) above the bottom of the incline. The incline is slippery, but there is some friction present, with kinetic friction coefficient \(\mu_{\mathrm{k}}.\) Use the work- energy theorem to calculate the minimum speed you must give the box at the bottom of the incline so that it will reach the skier. Express your answer in terms of \(g, h, \mu_{\mathrm{k}},\) and \(\alpha\).

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A sled with mass 8.00 \(\mathrm{kg}\) moves in a straight line on a frictionless horizontal surface. At one point in its path, its speed is \(4.00 \mathrm{m} / \mathrm{s} ;\) after it has traveled 2.50 \(\mathrm{m}\) beyond this point, its speed is 6.00 \(\mathrm{m} / \mathrm{s}\) . Use the work-energy theorem to find the force acting on the sled, assuming that this force is constant and that it acts in the direction of the sled's motion.

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