Calculate Crumple Zone Rigidty?

  • Thread starter Thread starter AJ22
  • Start date Start date
Click For Summary

Homework Help Overview

The discussion revolves around calculating the rigidity of a vehicle's crumple zone following a collision, specifically using kinetic energy and work-energy principles. The subject area includes concepts from physics related to energy, force, and vehicle safety design.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to apply the work-energy principle to determine crumple zone rigidity, questioning the angle used in the work equation during a collision. Other participants express uncertainty about the validity of this approach and seek clarification on the calculation method.

Discussion Status

Some participants have provided affirmations regarding the original poster's calculations, while others are questioning the method of determining crumple zone rigidity. There is an exploration of practical measurement methods, indicating a productive direction in the discussion.

Contextual Notes

Participants are discussing assumptions related to the angle in the work equation and the practical implications of measuring crumple zone rigidity, indicating potential gaps in information regarding standard practices in vehicle safety assessments.

AJ22
Messages
2
Reaction score
0
Homework Statement
Given the change in kinetic energy and distance, find the constant force needed in the crumple zone to stop the vehicle.
Relevant Equations
Work Energy Theorem: W = ΔEk
W = FcosxΔd
The vehicle comes to a stop after the collision so my kinetic energy is equal to (2000kg)(22m/s)2 / 2.
(Ekfinal -Ekinital)
I used the equation FcosxΔd = ΔEk. Knowing that the kinetic energy is -484000J and the length of the crumple zone is 0.70m, I can substitute those values into the equation.
Fcosx(0.70) = -484000.
My question is what would be the angle in the equation of W = FcosxΔd. During a collision the force from a wall acts in the opposite direction from the force of the crumple zone? So the angle is cos180 degrees = -1. Is this right?
So the constant force would then be F = -484000/-0.70 = 691Kn?
That means this number is also the crumple zone rigidity.
 
Last edited:
Physics news on Phys.org
Is that how crumple zone rigidity is calculated??
 
AJ22 said:
Is that how crumple zone rigidity is calculated??
In practice? I don’t know. It might be measured simply by squeezing it with a hydraulic ram.
 

Similar threads

Crumple zone in cars and ways to measure its effectiveness
  • · Replies 8 ·
Replies
8
Views
7K
Finding Acceleration of a Car Where Crumpling Occurs (Momentum)
  • · Replies 9 ·
Replies
9
Views
2K
Crumple Zone -Need help to better understand por favor
  • · Replies 1 ·
Replies
1
Views
4K
Forces applied to occupants in car crash (important for assignment )
  • · Replies 2 ·
Replies
2
Views
2K
Calrification on the physics of a car crumple zone.
  • · Replies 1 ·
Replies
1
Views
3K
Acceleration in One Dimensional Inelastic Collision
  • · Replies 33 ·
2
Replies
33
Views
4K
Question on Momentum, Force and Impulse
  • · Replies 1 ·
Replies
1
Views
2K
High School Car Crash Physics: Deceleration Calculations
  • · Replies 46 ·
2
Replies
46
Views
11K
What are the effects of different braking scenarios on cars and occupants?
  • · Replies 2 ·
Replies
2
Views
2K
How Does a Longer Crumple Zone Affect Impact Duration and Passenger Safety?
  • · Replies 2 ·
Replies
2
Views
3K