/*! 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 17 A \(5000-\) lb truck is being us... [FREE SOLUTION] | 91Ó°ÊÓ

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A \(5000-\) lb truck is being used to lift a 1000 -lb boulder \(B\) that is on a 200 -lb pallet \(A\). Knowing the acceleration of the truck is \(1 \mathrm{ft} / \mathrm{s}^{2}\), determine \((a)\) the horizontal force between the tires and the ground, (b) the force between the boulder and the pallet.

Short Answer

Expert verified
(a) 192.55 lb, (b) 37.27 lb.

Step by step solution

01

Identify the Forces

First, identify all the forces acting on the system. The truck has a weight of 5000 lb, the boulder has a weight of 1000 lb, and the pallet has a weight of 200 lb. These weights act downward due to gravity. The truck also exerts a horizontal force to accelerate.
02

Calculate Total Mass

The total mass being accelerated by the truck includes the truck itself, the boulder, and the pallet. Convert these weights to masses using the relation: \( m = \frac{W}{g} \), where \( g = 32.2 \frac{ft}{s^2} \). Thus, the total mass \(M_{total}\) is:\[ M_{total} = \frac{5000 + 1000 + 200}{32.2} \approx 192.55 \text{ slugs} \]
03

Use Newton's Second Law for Horizontal Force

Apply Newton’s second law to find the horizontal force \( F \). The equation is given by: \( F = M_{total} \cdot a \), with \( a = 1 \frac{ft}{s^2} \). So:\[ F = 192.55 \times 1 = 192.55 \text{ lb} \]
04

Determine Force on Boulder by Pallet

To find the force between the boulder and the pallet, consider only the boulder and the pallet. The force required to accelerate them together horizontally is found using:\[ M_{boulder\, +\, pallet} = \frac{1000 + 200}{32.2} = 37.27 \text{ slugs} \]Thus, the force is:\[ F_{b+p} = 37.27 \times 1 = 37.27 \text{ lb} \]

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Key Concepts

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

Forces in Mechanics
Understanding forces in mechanics is crucial for analyzing problems involving motion. Forces are interactions that can change the motion of an object. They are vector quantities, meaning they have both magnitude and direction.

In mechanics, several types of forces can be acting on objects:
  • Gravitational force: This is the force pulling objects towards the center of the Earth, commonly perceived as weight.
  • Normal force: Acts perpendicular to the surface that an object is in contact with.
  • Frictional force: Resists the motion of an object sliding on a surface.
  • Applied force: Exerted by objects or entities, such as the truck's force in the problem.
When analyzing a system of forces, as with the truck, boulder, and pallet, it is important to identify all acting forces. This process often involves breaking down the forces into components and considering their impact in different directions.
Mass and Weight Conversion
In physics, understanding the difference between mass and weight is essential. Mass is the measure of the amount of matter in an object and does not change regardless of the object's location. The weight of an object, on the other hand, is the force exerted by gravity on it.

To convert weight to mass in the imperial system, use the formula: \[ m = \frac{W}{g} \] where \( W \) is the weight in pounds and \( g \) is the gravitational acceleration (32.2 ft/s²).
  • For example, the truck in the problem has a weight of 5000 lb, which converts to mass by dividing by the gravitational constant.
  • This conversion is crucial for calculating how these objects behave under different forces, especially when using Newton's second law.
This distinction and conversion make analyzing forces and motions in problems much more manageable, ensuring accurate results.
Horizontal Force Calculation
Calculating horizontal forces often involves applying Newton's second law of motion, which relates net force, mass, and acceleration. According to Newton's second law, the formula is: \[ F = M \cdot a \] Where \( F \) is the net force applied, \( M \) is the mass, and \( a \) is the acceleration.

In the exercise, to determine the horizontal force exerted by the truck's wheels on the ground, you first calculate the total mass of the truck, boulder, and pallet.
  • Once the total mass is computed using weight-to-mass conversion, the acceleration given in the problem (1 ft/s²) helps establish the horizontal force.
  • The calculated force of 192.55 lb represents the necessary force to move the entire system horizontally at the given acceleration.
  • Understanding these calculations helps in realizing how much force is required to move different mass combinations horizontally.
This approach is vital in engineering applications, helping to design systems capable of moving objects efficiently.

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Most popular questions from this chapter

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A 4 -kg projectile is fired vertically with an initial velocity of \(90 \mathrm{m} / \mathrm{s}\), reaches a maximum height, and falls to the ground. The aerodynamic drag \(\mathrm{D}\) has a magnitude \(D=0.0024 \mathrm{v}^{2}\) where \(D\) and \(v\) are expressed in newtons and \(\mathrm{m} / \mathrm{s}\), respectively. Knowing that the direction of the drag is always opposite to the direction of the velocity, determine \((a)\) the maximum height of the trajectory, (b) the speed of the projectile when it reaches the ground.

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