Motion in one dimension physics problem

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SUMMARY

The discussion focuses on calculating stopping distances for an automobile with an initial speed of 90 km/h and a human reaction time of 1.0 seconds. For an acceleration of -5.0 m/s², the total stopping distance is 23 meters, while for an acceleration of -7.5 m/s², the stopping distance is 21 meters. The calculations utilize the equations of motion, specifically the formula s = ut + (1/2)at², where u is the initial speed, a is the acceleration, and t is the time. The initial speed is converted to 25 m/s for accurate calculations.

PREREQUISITES
  • Understanding of kinematic equations in physics
  • Knowledge of units conversion (km/h to m/s)
  • Familiarity with concepts of acceleration and deceleration
  • Basic understanding of human reaction time in motion scenarios
NEXT STEPS
  • Study the derivation and application of kinematic equations in real-world scenarios
  • Explore the effects of varying acceleration on stopping distances
  • Learn about the impact of human factors on driving performance and reaction times
  • Investigate advanced topics such as braking distance calculations under different conditions
USEFUL FOR

This discussion is beneficial for physics students, automotive engineers, and anyone interested in understanding the dynamics of vehicle stopping distances and the factors influencing them.

vv_ramirez259
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Homework Statement



Determine the stopping distances for an automobile with an initial speed of 90 and human reaction time of 1.0 : (a) for an acceleration = -5.0 , (b) for = -7.5 .

Homework Equations



vf = vo + at
avg velocity = (vf + vo) /2
d = vo)t + (1/2) at2
vf2 = vo2 + 2ad

The Attempt at a Solution




For part A)I tried using the formula s=ut+1/2at^2, I had that
u=25m/s, t=1.0s, a=-5.0,and then solved for s, which was =23m

For part B) I used the same formula and everything else was
the same, except for this part I let a=-7.5, which was = 21m
 
Physics news on Phys.org
The 1.0 seconds is the time before the driver steps on the brakes and starts accelerating. During that time he travels at constant speed. How far? Add that to the distance that he travels once he starts braking.
 

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