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How to do this physics problem?

How to do this physics problem? - Physics Forum

How to do this physics problem? - Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


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Old 06-23-2009, 08:17 PM
Pipette Filler
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Default How to do this physics problem?



A person who is properly constrained by a shoulder harness has a good chance of surviving a car collision if the deceleration does not exceed 30 g's. Assuming uniform deceleration at this rate, calculate the distance over which the front end of the car must be designed to collapse if a crash occurs at 100km/hr.

-Solve for hood disance

-Convert to meters per second

-show your work


This is the exact question and im stuck. plz help
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Old 06-23-2009, 08:17 PM
Pipette Filler
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Not a hard question if you know the relation

v^2 = u^2 +2as
when there is a collision , the final velocity is always 0 because the car has to stop, rite!... ok. so v=0
u is given as 100km/h. convert it to m/s . it would be u=27.7m/s(assuming u know how to convert)
k so a=acceleration.. it is given as 30g.s convert it into m/s^2 . it would be 30x9.8 = 294m/s^2
now plug all the values into the equation.
0=(27.7)^2 - 2(294) S ;S=distance. there is a negative bc it is deceleration.
so S=1.31m
answer is 1.31m
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