Calculating Average Acceleration: Solving a Sports Car Stopping Distance Problem

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Homework Help Overview

The discussion revolves around calculating the average acceleration of a sports car based on its stopping distance and initial speed. The problem involves concepts from kinematics, specifically relating to motion and acceleration.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the method used to calculate average acceleration, including the formula applied and the conversion of speed from km/h to m/s. Questions arise regarding the accuracy of the initial calculations and the importance of the sign of acceleration.

Discussion Status

The discussion is active, with participants providing feedback on calculations and questioning the assumptions made in the problem. There is acknowledgment of potential issues with the sign of the acceleration and the method used, but no consensus has been reached on the final answer.

Contextual Notes

Participants note that the problem may require attention to significant figures and the proper interpretation of acceleration in terms of direction. There is also mention of the need for additional information to determine instantaneous acceleration, which is not provided in the problem.

slayerdeus
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A sports car is advertised to be able to stop in a distance of 44 m from a speed of 95 km/h. What is its [average] acceleration in m/s2? How many g's is this (g = 9.80 m/s2)?

I have 7.9 m/s2, as my answer for average acceleration, but webassign isn't accepting my answer. Can someone help me out?
 
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How did you arrive at that answer?
 
I used v^2-vo^2=2a(x-xo

Have to convert to m/s so vo=26.38 m/s, vf=0
 
Looks right to me; however:
Did you remember the sign on the acceleration?

That's about what I can think of, unless you were supposed to enter the number of g's the acceleration is in
 
Not 26.39?
 
yea its 26.38888888888 m/s, no it asks for g's in another questions and when I do 7.9/9.8 it says that answer is correct. I wonder if this method is average acceleration or is it instantaneous?
 
It absolutely cannot be the inst. acceleration they're after; in order to know this, you would need a lot more information (effect of brakes, frictional coefficient etc.)

Since your second answer is correct, I can see only 2 possibilities:
a) The machine is wrong
b) It requires a sign for the acceleration

On second thought: Have you tried using velocity 26.4 and rounding off to one significant decimal?
 
Still average. You have no knowledge of the interior, only the endpoints.

cookiemonster
 
Okay, thanks mucho. It was the sign :rolleyes:
 

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