What causes the acceleration of a car's suspension after hitting a road bump?

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Homework Help Overview

The discussion revolves around the acceleration of a car's suspension system after encountering a road bump, specifically in the context of simple harmonic motion (SHM). Participants are examining a quiz question regarding the expected variation of acceleration with time.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are questioning the accuracy of the quiz's answer, which suggests a straight line for acceleration, while others argue that the correct representation should be sinusoidal. There is also discussion about the effects of damping on the suspension system's behavior.

Discussion Status

The conversation is ongoing, with participants exploring different interpretations of the quiz question and the underlying physics. Some have provided insights into the relationship between acceleration and displacement, while others are questioning the clarity of the quiz's wording and its implications.

Contextual Notes

There is mention of damping in the suspension system, which may affect the observed oscillations, and participants are considering how this factor influences the expected graph of acceleration over time.

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Homework Statement


Ok, I was stumped by this simple online quiz which asked the variation of acceleration with time of a suspension unit of a car after a road bump which follows SHM. (HC0809)

A. Straight line
B. Ellipse
C. Circle
D. Parabola

The Attempt at a Solution



The answer was supposed to be sinusoidal and the quiz gave the answer as A, straight line but that is obviously wrong since

[tex]a=-w^2x[/tex]

And the correct form is

[tex]a=-w^2x_0sinwt[/tex]

Am i missing something, is the quiz wrong
 
Last edited:
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Was that the exact wording? Maybe there is something you've missed...

Real suspensions also have damping and under particular conditions the oscillation is barely observable... but I don't think a "straight line" would ever be correct for the acceleration.
 
nooooooo... the acceleration-displacement graph is a negative gradient straight line, through origin. and the equation is a = -w^2X0

at least this is what we learn in high school...
 
If you graph acceleration vs. displacement it is indeed a straight line

with a slope of -w^2, as given by his equation a=-w^2*x

However that's not what he was asked for, unless he read the question wrong. Maybe the question made that slip up
 
mda said:
Was that the exact wording? Maybe there is something you've missed...

Real suspensions also have damping and under particular conditions the oscillation is barely observable... but I don't think a "straight line" would ever be correct for the acceleration.

yes there was damping mentioned in the question but I don't see how a straight line could every beformed if the graph was an acceleration time one
 

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