Calculating Average Force in a Car Collision

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SUMMARY

The average force exerted on a 1200 kg car during a collision with a brick wall, where it initially travels at 14 m/s and rebounds at 3 m/s over a duration of 0.10 seconds, can be calculated using the formula F = m * Δv / Δt. The correct change in velocity is 17 m/s, calculated as (final velocity - initial velocity), which is 3 m/s - 14 m/s. The resulting average force is 204,000 N, although it is crucial to ensure the correct unit for force is included in the final answer.

PREREQUISITES
  • Understanding of Newton's Second Law (F=ma)
  • Knowledge of kinematic equations for calculating change in velocity
  • Familiarity with units of force (Newtons)
  • Basic algebra for manipulating equations
NEXT STEPS
  • Review the concept of impulse and momentum in collisions
  • Learn about the significance of sign conventions in physics
  • Explore real-world applications of average force calculations in crash testing
  • Investigate the effects of different collision durations on force calculations
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and collision dynamics, as well as educators looking for practical examples of force calculations in real-world scenarios.

ScullyX51
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Homework Statement


A 1200 kg car drives headlong into a brick wall at 14 m/s and rebound at 3 m/s. The collision lasts for .10 seconds. What is the average force on the car during the collision?


Homework Equations


F=ma
f*change in time= mass * change in velocity
f= mass*change in velocity / change in time


The Attempt at a Solution


I got the change in velocity to be 17 m/s. I did 14 m/s - (-3m/s) = 17 (I put the 3 as negative since it it rebounding it is going in the negative x direction.
f= 1200(17)/ .1 = 204,000. this is wrong..where am I messing up?
 
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ScullyX51 said:

Homework Statement


A 1200 kg car drives headlong into a brick wall at 14 m/s and rebound at 3 m/s. The collision lasts for .10 seconds. What is the average force on the car during the collision?


Homework Equations


F=ma
f*change in time= mass * change in velocity
f= mass*change in velocity / change in time


The Attempt at a Solution


I got the change in velocity to be 17 m/s. I did 14 m/s - (-3m/s) = 17 (I put the 3 as negative since it it rebounding it is going in the negative x direction.
f= 1200(17)/ .1 = 204,000. this is wrong..where am I messing up?
The change in velocity is (final v - initial v). You may have a signage error. And don't forget the force unit.
 
Looks good to me, except for you not including the correct unit for force.
 

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