Average G-Force Calculation for Abrupt Deceleration from 30mph in 1m Distance

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Homework Help Overview

The problem involves calculating the average g-force experienced during an abrupt deceleration from an initial speed of 30 mph over a distance of 1 meter, typically in the context of a car crash scenario.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of kinematic equations to find acceleration and time, questioning the conversion of units from mph to m/s and the implications of the calculated acceleration value.

Discussion Status

Some participants have provided insights into the values of final velocity and distance, while others are exploring the implications of their calculations and questioning the correctness of their unit conversions. There is an ongoing examination of the assumptions made in the problem setup.

Contextual Notes

Participants note the need to convert units properly and ensure that acceleration is expressed in m/s², highlighting potential confusion regarding the calculations and the physical interpretation of the results.

bond535
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Homework Statement


Determine the average number of g's experienced by someone abruptly coming to rest from an initial velocity of 30mph (such as in a car crash). Take the distance involved in coming to rest to be 1 m.

Homework Equations


V=Vo+at
ΔS=volt+1/2at^2
V^2=Vo^2+2aΔS

The Attempt at a Solution


t=?
a=?
Vo= 30 mph
V=?
ΔS=?

Thank you, I'm really stuck and any help will be deeply appreciate it.
 
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You know Vfinal = 0 and ΔS (change in distance) = 1m. does that help?
 
so...
t=?
a=?
Vo= 30 mph
V=0
ΔS=1m

V^2=Vo^2+2aΔS
0=(30mph)^2+2a(1m)
which resulted in a= -450mph

I know g= 9.8m/s ... so I'm assuming I have to change the -450mph to m/s by diving -450/3600s = 0.125m/s

I really don't know what to do next or if I'm in the right track...
 
V^2=Vo^2+2aΔS
0=(30mph)^2+2a(1m)
which resulted in a= -450mph
a should be in units of m/s2

(convert mph to m/s)
 

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