Calculating Net Force and Deacceleration in a Head-On Collision

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SUMMARY

The discussion focuses on calculating the net force experienced by a 58 kg person in a head-on collision at a speed of 13 m/s, considering the effects of a seatbelt and airbag deployment. The participant correctly applies the kinematic equation to determine the deceleration over a distance of 1 meter, resulting in an acceleration of -84.5 m/s². Using this value, they calculate the net force as -4901 N. However, the participant questions the accuracy of their result, suggesting a potential misunderstanding of the physics involved in the collision dynamics.

PREREQUISITES
  • Understanding of Newton's second law of motion (Force = mass * acceleration)
  • Familiarity with kinematic equations, specifically the equation for final velocity
  • Basic knowledge of significant figures in scientific calculations
  • Concept of deceleration and its impact during collisions
NEXT STEPS
  • Review the principles of momentum conservation in collisions
  • Study the effects of seatbelts and airbags on occupant safety during collisions
  • Learn about the role of significant figures in physics calculations
  • Explore advanced kinematic equations for varying distances and accelerations
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and collision dynamics, as well as individuals interested in automotive safety and engineering principles.

Sky.Anthony
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Homework Statement



A 58 kg person is in a head-on collision. The car's speed at impact is 13 m/s. Estimate the net force on the person if he or she is wearing a seat belt and if the air bag deploys.

For some reason, I can't seem to get the correct answer to this question... I have no idea where I am going wrong. According to the question, if a person is wearing a seatbelt, they deaccelerate over a distance of 1m.

Homework Equations



(Final Velocity)^2 = (Initial Velocity)^2 + 2*acceleration*distance
Force=mass*acceleration

The Attempt at a Solution



First off, I had to find the deacceleration over the distance of 1m:
(Final Velocity)^2 = (Initial Velocity)^2 + 2*acceleration*distance
0 = (13m/s)^2 + 2*acceleration*1m
acceleration= -84.5m/s^2

Using that acceleration to calculate net force...
F=ma
= (58kg)(-84.5m/s^2)
=-4901N

I put that answer into the system and it comes back wrong...

Help is appreciated. Thanks!
 
Physics news on Phys.org
well it sound reasonable to me
but thinking back if a person wearing seatbelt should they move forward then move back ward?
 
Don't forget about your significant figures.
 

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