Acceleration given velocity and distance

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SUMMARY

The average acceleration of the driver during the collision is calculated to be -37.08 g's, derived from an initial speed of 90 km/h and a stopping distance of 0.86 m. The acceleration in meters per second squared is confirmed as -363.37 m/s². The conversion from m/s² to g's is accurately performed by dividing by 9.81, affirming that negative acceleration is valid in this context. There are no limits on negative g's, as they simply indicate deceleration.

PREREQUISITES
  • Understanding of basic physics concepts, particularly kinematics.
  • Familiarity with unit conversions, specifically between kilometers per hour and meters per second.
  • Knowledge of acceleration calculations and the concept of gravitational force (g).
  • Ability to apply equations of motion in collision scenarios.
NEXT STEPS
  • Review kinematic equations for motion under constant acceleration.
  • Study the effects of deceleration in collision physics.
  • Learn about the implications of negative acceleration in real-world scenarios.
  • Explore advanced topics in vehicle dynamics and safety measures during collisions.
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Students studying physics, automotive engineers, safety analysts, and anyone interested in understanding the dynamics of vehicle collisions and acceleration calculations.

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Homework Statement


A car traveling at 90 km/h strikes a tree. The front end of the car compresses and the driver comes to rest after traveling 0.86 m. What was the average acceleration in g's of the driver during the collision?

Homework Equations


The Attempt at a Solution


The acceleration in m/s/s is -363.37 but I tried dividing by 9.8 and I got -37.05 g's but evidently that's wrong. I'm not sure what I'm missing here, I converted the km/h into m/s/s then got the correct acceleration then devided by 9.81. Is there a rule that I didn't use? Is there a limit on negative gs?
 
Last edited:
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You are right, the acceleration is -363.37 m/s/s.

I'm not a hundred percent sure, but I think -37.08 g's is actually correct. Because if one g is worth 9.8 m/s/s, and you had positive 37.08 of them, your acceleration would be in the positive direction. But it's not... so I see no problem with having a negative number there.

Is there another reason you think -37 g's is wrong?
 

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