Machine Elements - Module 6 Quiz
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Questions and Answers

Acceleration analysis involves determining how certain points on links of a mechanism are either speeding up or slowing down. What is this property critical for, in terms of the forces associated with it?

Inertia

In the study of forces, Sir Isaac Newton discovered that inertial forces are proportional to what?

Acceleration

What is the primary procedure utilized in analyzing accelerations in a linkage?

  • Dynamic analysis
  • Velocity method
  • Relative acceleration method (correct)
  • Kinematic analysis

    • Graphical and analytical techniques are utilized in acceleration analysis.

    <p>True</p> Signup and view all the answers

    Which of these terms are used to describe acceleration? (Select all that apply)

    <p>Tangential</p> Signup and view all the answers

    What is the symbol used to designate the magnitude of the acceleration vector?

    <p>a</p> Signup and view all the answers

    The magnitude of linear acceleration is expressed in units of what?

    <p>Velocity (length per time) divided by time</p> Signup and view all the answers

    Which of these units are commonly used for linear acceleration in the International System? (Select all that apply)

    <p>m/s²</p> Signup and view all the answers

    What term describes the velocity change caused by a constant acceleration?

    <p>Constant Rectilinear Acceleration</p> Signup and view all the answers

    The equation Vfinal = Vinitial + AΔt represents what?

    <p>Velocity change</p> Signup and view all the answers

    The equation ΔR = 1/2 AΔt² + VinitialΔt represents what?

    <p>Displacement</p> Signup and view all the answers

    What is the standard acceleration due to gravity on Earth?

    <p>32.17 ft/s² or 9.81 m/s²</p> Signup and view all the answers

    The relative acceleration method utilizes the results of the relative velocity method.

    <p>True</p> Signup and view all the answers

    What does angular acceleration of a link refer to?

    <p>Angular velocity per unit time</p> Signup and view all the answers

    What is the preferred unit of angular acceleration?

    <p>Radians per squared second (rad/s²))</p> Signup and view all the answers

    Which aspect of acceleration results from a change in the direction of the velocity vector?

    <p>Normal acceleration</p> Signup and view all the answers

    Which aspect of acceleration results from a change in the magnitude of the velocity vector?

    <p>Tangential acceleration</p> Signup and view all the answers

    The magnitude of tangential acceleration is represented by the equation at = a * r , where 'a' is the angular acceleration and 'r' is the distance from the point to the center of rotation.

    <p>True</p> Signup and view all the answers

    What is the key takeaway regarding the direction of the tangential acceleration?

    <p>It is aligned with the direction of motion and acts in the direction of increasing velocity.</p> Signup and view all the answers

    The equation an = v²/r represents the magnitude of normal acceleration, where 'v' is the velocity and 'r' is the radius of curvature.

    <p>True</p> Signup and view all the answers

    What important concept does normal acceleration highlight?

    <p>The direction of the velocity vector changes.</p> Signup and view all the answers

    The total acceleration of a moving point is the sum of the normal and tangential components.

    <p>True</p> Signup and view all the answers

    What is the equation for the total acceleration of a moving point?

    <p>A = at + an</p> Signup and view all the answers

    Why is acceleration analysis important for a machine's design?

    <p>To ensure the machine is adequately designed to handle the dynamic loads created by inertial forces.</p> Signup and view all the answers

    What is the definition of relative velocity?

    <p>The velocity of one object as observed from another reference object that is also moving.</p> Signup and view all the answers

    What is the definition of relative acceleration?

    <p>The acceleration of one object as observed from another reference object that is also moving.</p> Signup and view all the answers

    The equation AB/A = acceleration (total) of point B 'as observed' from point A represents the relative acceleration.

    <p>True</p> Signup and view all the answers

    Relative acceleration can be broken down into normal and tangential components.

    <p>True</p> Signup and view all the answers

    What is the equation for the relative acceleration?

    <p>aB/A = aB - aA</p> Signup and view all the answers

    What is the Coriolis effect?

    <p>The deflection of moving objects when viewed from a rotating reference point.</p> Signup and view all the answers

    In the context of Coriolis effect, what is the coincident point?

    <p>The point on the rotating link where the point on a sliding link is located.</p> Signup and view all the answers

    The Coriolis acceleration is always perpendicular to the direction of the relative velocity.

    <p>True</p> Signup and view all the answers

    Why is it important to consider the Coriolis effect?

    <p>It must be considered when a point on a link slides along a rotating link, like in mechanisms such as crank and slotted lever mechanisms or a Whitworth quick return mechanism.</p> Signup and view all the answers

    Study Notes

    Course Information

    • Course title: Machine Elements
    • Module: 6
    • Department: Mechanical Engineering Department
    • University: Bulacan State University
    • City/Location: Malolos, Bulacan

    Unit 6: Acceleration Analysis

    • Lessons covered:
      • Linear Acceleration
      • Acceleration of a Link
      • Normal and Tangential Acceleration
      • Relative Motion
      • Relative Acceleration using Graphical Method
      • Coriolis Acceleration using Graphical Method
    • Duration: 4 hours
    • Pretest:
      • A pre-test is conducted to assess student preparedness before the lesson.
      • Graphical method is used to determine the instantaneous velocity of a Whitworth mechanism.
      • Dimensions provided: BC = 40 cm, AD = 25 cm, DQ = 75 cm.

    Introduction

    • Acceleration analysis involves determining how points on mechanisms speed up or slow down.
    • Acceleration is crucial because it relates to inertial forces.
    • Inertia force is proportional to the acceleration of a body.

    Objectives/Competencies

    • Define linear, rotational, normal, tangential, Coriolis, and relative accelerations.
    • Use the relative acceleration method to determine the acceleration of a point on a link when another point's acceleration is known
    • Use the relative acceleration method to determine the acceleration of a point on a moving component.
    • Understand when Coriolis acceleration is present in a mechanism.

    Lesson 6.1: Linear Acceleration

    • Linear acceleration (A) is the change in linear velocity with respect to time.
    • The magnitude of acceleration is denoted by |A|.
    • The magnitude of acceleration, if velocity is constant is given by
    • A = dv/dt
    • A = d^2r/dt^2
    • Angular acceleration is the rate of change of angular velocity (a = dw/dt).
    • For short periods of time, angular acceleration can be assumed to be linear.

    Lesson 6.3: Normal and Tangential Acceleration

    • Normal acceleration is directed towards the center of rotation, resulting from a change in the velocity direction.
    • Tangential acceleration is perpendicular to the line connecting the point to the center of rotation, due to a change in the velocity magnitude.

    Lesson 6.4: Relative Motion

    • Relative motion is the motion of one point of a mechanism as observed from another point in the mechanism.
    • Method for relative acceleration calculation is discussed.

    Lesson 6.5: Relative Acceleration Using Graphical Method

    • Graphical methods are used to determine the instantaneous acceleration of points within a mechanism.

    Lesson 6.6: Coriolis Acceleration using Graphical Methods

    • This lesson explores the Coriolis effect when a point slides along a rotating link.
    • The Coriolis acceleration is considered in cases like slider-crank and Whitworth quick return mechanisms.

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    Related Documents

    Module 6 Acceleration Analysis PDF

    Description

    Test your understanding of acceleration analysis in machine elements. This quiz covers various aspects, including linear acceleration, relative motion, and the graphical methods for determining accelerations. Prepare to assess your knowledge on crucial concepts that impact inertial forces in mechanisms.

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