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A person pulls a toboggan for a distance of \(35.0 \mathrm{m}\) along the snow with a rope directed \(25.0^{\circ}\) above the snow. The tension in the rope is 94.0 N. (a) How much work is done on the toboggan by the tension force? (b) How much work is done if the same tension is directed parallel to the snow?

Short Answer

Expert verified
(a) 2982.18 J; (b) 3290 J.

Step by step solution

01

Understanding Work Done by a Force

To calculate the work done by a force, we apply the formula: \[ W = F imes d imes \cos(\theta) \]where \( W \) is the work done, \( F \) is the force applied, \( d \) is the distance moved, and \( \theta \) is the angle between the force and the direction of movement.
02

Calculate Work with Angled Force

Given that the tension \( F = 94.0 \) N, the distance \( d = 35.0 \) m, and the angle \( \theta = 25.0^{\circ} \), we can substitute these values into the formula:\[W = 94.0 \times 35.0 \times \cos(25.0^{\circ})\]
03

Simplify Using Cosine

Calculate \( \cos(25.0^{\circ}) \) using a calculator to get approximately 0.906.Substitute into the equation:\[W = 94.0 \times 35.0 \times 0.906\]
04

Final Calculation for Work with Angled Force

Perform the multiplication:\[W \approx 94.0 \times 35.0 \times 0.906 \approx 2982.18 \text{ J (joules)}\]
05

Calculate Work with Parallel Force

If the force is directed parallel to the snow (\(\theta = 0^{\circ}\)), then:\[W = 94.0 \times 35.0 \times \cos(0^{\circ})\]Since \(\cos(0^{\circ}) = 1\), this simplifies to:\[W = 94.0 \times 35.0 = 3290 \text{ J (joules)}\]

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Key Concepts

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

Work Done by a Force
Work is a measure of energy transfer when a force acts upon an object to cause a displacement. The concept of work done by a force is fundamental in physics, describing how effectively a force can move an object over a distance. To quantify this, we use the formula:
  • \( W = F \times d \times \cos(\theta) \)
Here, \(W\) represents the work done in joules (J), \(F\) is the magnitude of the force in newtons (N), \(d\) is the distance in meters (m), and \(\theta\) is the angle between the line of action of the force and the direction of movement.
For example, when pulling a toboggan, the force exerted by the rope over the distance is what generates work. The cosine factor accounts for the angle of application, adjusting the effective force that actually contributes to the movement. If the angle is zero, the force is fully effective, while if the angle is 90 degrees, no work is done since the force acts perpendicular to the direction of displacement.
Understanding this relationship helps in calculating the work done in various scenarios, as seen with the toboggan example, where the force was angled above the snow.
Angle of Force Application
The angle of force application plays a critical role in determining how much of a force contributes to the work done on an object. In the formula for work, the cosine of the angle \( \theta \) is significant because it adjusts the magnitude of the force that effectively influences the displacement. Here are a few key considerations:
  • An angle of \(0^{\circ}\) implies the force is applied directly in the direction of movement, maximizing work done.
  • Angles between \(0^{\circ}\) and \(90^{\circ}\) reduce the effective force proportionally to \( \cos(\theta) \).
  • At \(90^{\circ}\), the force is perpendicular to the movement, resulting in no work done.
In the context of the toboggan pulled at \(25^{\circ}\) above the snow, the angle reduces the effective tension force contributing to the movement. By calculating \( \cos(25^{\circ}) \), we adjust the total force to reflect just the part of it that moves the toboggan forward.
It's essential to calculate and understand the effect of this angle to solve problems involving inclined force application effectively.
Tension in Physics
Tension refers to the force transmitted through a string, rope, cable, or similar when it is pulled tight by forces acting from opposite ends. Tension is a crucial concept in physics, especially in problems involving vertical or horizontal forces. Here's what you need to know about tension:
  • Tension is a force; it has magnitude and direction and is measured in newtons (N).
  • In a simple rope system pulling an object, the tension typically remains constant along the rope as long as there's no additional friction or forces acting to change it.
In the toboggan example, the tension of 94.0 N in the rope signifies the pulling force used to move the toboggan. This force, when angled above the snow, partially contributes to moving the toboggan horizontally while the rest acts vertically.
Knowing the magnitude of tension helps calculate work done, especially since any angle can adjust how much tension truly contributes to motion. Understanding tension and how it interacts with angles and forces gives a deeper insight into solving complex physics problems easily and accurately.

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Most popular questions from this chapter

Bicyclists in the Tour de France do enormous amounts of work during a race. For example, the average power per kilo-gram generated by seven-time-winner Lance Armstrong \((m=75.0 \mathrm{kg})\) is \(6.50 \mathrm{W}\) per kilogram of his body mass. (a) How much work does he do during a \(135-\mathrm{km}\) race in which his average speed is \(12.0 \mathrm{m} / \mathrm{s} ?\) (b) Often, the work done is expressed in nutritional Calories rather than in joules. Express the work done in part (a) in terms of nutritional Calories, noting that 1 joule \(=2.389 \times 10^{-4}\) nutritional Calories.

A truck is traveling at \(11.1 \mathrm{m} / \mathrm{s}\) down a hill when the brakes on all four wheels lock. The hill makes an angle of \(15.0^{\circ}\) with respect to the horizontal. The coefficient of kinetic friction between the tires and the road is \(0.750 .\) How far does the truck skid before coming to a stop?

A basketball of mass \(0.60 \mathrm{kg}\) is dropped from rest from a height of \(1.05 \mathrm{m}\). It rebounds to a height of \(0.57 \mathrm{m}\). (a) How much mechanical energy was lost during the collision with the floor? (b) \(\mathrm{A}\) basketball player dribbles the ball from a height of \(1.05 \mathrm{m}\) by exerting a constant downward force on it for a distance of \(0.080 \mathrm{m}\). In dribbling, the player compensates for the mechanical energy lost during each bounce. If the ball now returns to a height of 1.05 m, what is the magnitude of the force?

A slingshot fires a pebble from the top of a building at a speed of \(14.0 \mathrm{m} / \mathrm{s} .\) The building is \(31.0 \mathrm{m}\) tall. Ignoring air resistance, find the speed with which the pebble strikes the ground when the pebble is fired (a) horizontally, (b) vertically straight up, and (c) vertically straight down.

Under the influence of its drive force, a snowmobile is moving at a constant velocity along a horizontal patch of snow. When the drive force is shut off, the snowmobile coasts to a halt. The snowmobile and its rider have a mass of \(136 \mathrm{kg}\). Under the influence of a drive force of \(205 \mathrm{N},\) it is moving at a constant velocity whose magnitude is \(5.50 \mathrm{m} / \mathrm{s}\) The drive force is then shut off. Find (a) the distance in which the snowmobile coasts to a halt and (b) the time required to do so.

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