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(II) What is the minimum work needed to push a \(950 - \mathrm { kg }\) car 310\(\mathrm { m }\) up along a \(9.0 ^ { \circ }\) incline? Ignore friction.

Short Answer

Expert verified
The minimum work needed is approximately 459,076.8 J.

Step by step solution

01

Identify Given Information

We have a car with a mass of 950 kg that needs to be moved up a 9.0-degree incline over a distance of 310 meters. We need to find the minimum work required, ignoring friction.
02

Determine Forces Involved

The force required to push the car up the incline without friction is equal to the component of the gravitational force pulling it down the incline. This force can be calculated using the formula: \[ F = m \cdot g \cdot \sin(\theta) \]where \( m = 950 \text{ kg} \), \( g = 9.8 \text{ m/s}^2 \), and \( \theta = 9.0^{\circ} \).
03

Calculate Force Component Along the Incline

Substitute the given values into the formula to find the force:\[ F = 950 \cdot 9.8 \cdot \sin(9.0^{\circ}) \].Calculate \( \sin(9.0^{\circ}) \) using a calculator. Substitute the values to find \( F \).
04

Calculate Minimum Work Done

The work done, \( W \), is determined using the formula:\[ W = F \cdot d \]where \( d = 310 \text{ m} \) is the distance traveled along the incline. Use the force calculated in the previous step to determine the work done.
05

Substitute and Solve

Substitute \( F \) from the previous step into the work formula:\[ W = 950 \cdot 9.8 \cdot \sin(9.0^{\circ}) \cdot 310 \]Use a calculator to find the final answer for work, \( W \).

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Key Concepts

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

Work-energy theorem
The work-energy theorem is a fundamental principle in physics that connects the concept of work with changes in energy. Simply put, this theorem states that the work done on an object is equal to the change in its kinetic energy. In mathematical terms, it can be expressed as:\[ W = rac{1}{2}mv_f^2 - rac{1}{2}mv_i^2 \]where:
  • \( W \) is the work done on an object,
  • \( m \) is the mass of the object,
  • \( v_f \) is the final velocity, and
  • \( v_i \) is the initial velocity.
In scenarios like pushing a car up an incline, understanding this theorem helps us recognize that the work done against gravity, besides changing the speed, might also increase the potential energy of the object. When there's no friction, and the speed doesn't change, all the work done translates into potential energy gain. This provides an elegant way to calculate the required work using the energy approach rather than analyzing individual forces.
Inclined plane
An inclined plane, or simply a slope, is a flat surface that is tilted at an angle to the horizontal. In physics problems, this angle introduces an interesting scenario where different components of forces come into play:
  • The incline angle \( \theta \) alters how gravitational force acts on an object. Instead of acting straight down, it now has two components: one parallel and one perpendicular to the surface.
  • The component parallel to the incline, responsible for pulling the object downwards, is given by \( m \, g \, \sin(\theta) \).
  • This parallel component is critical as it directly determines the force needed to push an object up the incline without slipping.
Using trigonometry, we easily decipher these components, greatly simplifying calculations like the minimum work needed to move an object along the plane. For a 9-degree incline, the effect is calculated using \( \sin(9^{\circ}) \), ensuring accurate results.
Gravitational force
Gravitational force is the attractive force between two masses, such as a car and the Earth. It is a cornerstone concept in physics and is crucial in understanding how objects behave on inclined planes.For any object near Earth's surface, gravitational force can be calculated as:\[ F_g = m \, g \]where:
  • \( F_g \) is the gravitational force,
  • \( m \) is the mass of the object, and
  • \( g \approx 9.8 \, \text{m/s}^2 \) is the acceleration due to gravity.
In the context of inclined planes, this force is split into two components:
  • A perpendicular component, \( m \, g \, \cos(\theta) \), which presses the object against the surface.
  • A parallel component, \( m \, g \, \sin(\theta) \), which pulls the object downwards along the incline.
Understanding these components is essential for calculating forces required to move objects up slopes, giving us new ways to apply the fundamentals of gravitational interactions.

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Most popular questions from this chapter

The net force along the linear path of a particle of mass \(480 \mathrm{~g}\) has been measured at \(10.0-\mathrm{cm}\) intervals, starting at \(x=0.0,\) to be 26.0,28.5,28.8,29.6,32.8,40.1,46.6,42.2 48.8,52.6,55.8,60.2,60.6,58.2,53.7,50.3,45.6,45.2,43.2,38.9 \(35.1,30.8,27.2,21.0,22.2,\) and \(18.6,\) all in newtons. Determine the total work done on the particle over this entire range.

A cyclist starts from rest and coasts down a 4.0^ \circ hill. The mass of the cyclist plus bicycle is 85\(\mathrm { kg }\) . After the cyclist has traveled \(250 \mathrm { m } ,\) (a) what was the net work done by gravity on the cyclist? (b) How fast is the cyclist going? Ignore air resistance.

How high will a \(1.85-\mathrm{kg}\) rock go if thrown straight up by someone who does \(80.0 \mathrm{~J}\) of work on it? Neglect air resistance.

\(\begin{array}{llll}\text { (II) } & \text { Suppose } & \mathbf{A}=1.0 \mathbf{i}+1.0 \mathbf{j}-2.0 \mathbf{k} & \text { and } & \mathbf{B}=\end{array}\) \(-1.0 \hat{\mathrm{i}}+1.0 \mathrm{j}+2.0 \hat{\mathbf{k}}, \quad(a)\) what is the angle between these two vectors? \((b)\) Explain the significance of the sign in part \((a)\).

In the game of paintball, players use guns powered by pressurized gas to propel \(33 -\) g gel capsules filled with paint at the opposing team. Game rules dictate that a paintball cannot leave the barrel of a gun with a speed greater than 85\(\mathrm { m } / \mathrm { s } .\) Model the shot by assuming the pressurized gas applies a constant force \(F\) to a \(33 - g\) capsule over the length of the \(32 - \mathrm { cm }\) barrel. Determine \(F ( a )\) using the work-energy principle, and \(( b )\) using the kinematic equations and Newton's second law.

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