Find the size of the force due to wind and rolling friction

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Homework Help Overview

The problem involves calculating the force due to wind and rolling friction for a van with a specified mass and speed. The context includes the conversion of speed from mph to m/s and the use of a graph to estimate acceleration.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the method of calculating acceleration from the graph and question the relevance of the weight given in pounds. There is also a suggestion to take the slope over the entire range of the graph.

Discussion Status

The discussion is ongoing with participants providing feedback on the original poster's calculations and questioning the details of the problem statement. Some guidance has been offered regarding the interpretation of the graph.

Contextual Notes

There is a mention of the problem's specific details, such as the precision of the speed measurement and the weight provided in pounds, which may not be necessary for the calculations.

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[SOLVED] Force Problem

The total mass is 2300kg (weight = 5072lbs). Find the size of the force due to wind and rolling friction when the van speed is 42.17mph (1mph= 0.447m/s).

This is the graph: http://capa-new.colorado.edu/msuphysicslib/Graphics/Gtype12/prob09a_1004minivan.gif"

F = ma

a = (speed 2 - speed 1)/(Time 2 - Time 1)

Converted mph to m/s: a = (26.82 - 18.85)/(23) = 0.3465 m/s^2

Now F = (2300*0.3465) = 797 N

What did I do wrong?
 
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You didn't do much wrong. Your graph looks a bit nonlinear, but I don't see how they would expect you to read much more than a rough estimate off of it. Is that really the statement of the problem? 42.17mph!? Four decimal places?
 
Last edited:
Take the slope over the entire range of the graph.
 
That's what I'm assuming... they gave me the weight in lbs. do I need to incorporate that into my equations in any way or is that just unnecessary/useless info.
 
ohhi thanks a lot !
 

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