What is the maximum reaction time to avoid hitting the deer?

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SUMMARY

The discussion focuses on calculating the maximum reaction time for a ranger driving at 28.0 mi/h to avoid hitting a deer 155 ft ahead. Using the equations of motion, the ranger's initial speed converts to 41.06667 ft/s. With a deceleration of -9.00 ft/s², the calculations reveal that the maximum allowable reaction time is approximately 2.5 seconds, ensuring the vehicle stops before reaching the deer.

PREREQUISITES
  • Understanding of kinematic equations, specifically V = V₀ + at and V² = V₀² + 2a(Δx)
  • Basic knowledge of unit conversions, particularly from miles per hour to feet per second
  • Familiarity with concepts of acceleration and deceleration in physics
  • Ability to solve quadratic equations
NEXT STEPS
  • Study the derivation and application of kinematic equations in real-world scenarios
  • Learn about unit conversion techniques, especially for speed and distance
  • Explore the effects of different deceleration rates on stopping distances
  • Investigate the implications of reaction time in emergency vehicle operations
USEFUL FOR

This discussion is beneficial for physics students, automotive safety engineers, and anyone interested in understanding vehicle stopping distances and reaction times in emergency situations.

nfxgosu
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A ranger in a national park is driving at 28.0 mi/h when a deer jumps into the road 155 ft ahead of the vehicle. After a reaction time t, the ranger applies the brakes to produce an acceleration of a = -9.00 ft/s2. What is the maximum reaction time allowed if she is to avoid hitting the deer?



V=(Vo)(t)+(1/2)at^2
V^s=(Vo)^2+2a(delta x)


28.0 mi 5280 ft 1 hr = 41.06667ft/s
1 hr 1 mi 3600 s
 
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Start by figuring out the distance she needs to come to a stop. (Use one of the equations you posted.)
 

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