How can kinematics problems be solved with reaction time taken into account?

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SUMMARY

The discussion focuses on solving kinematics problems by incorporating reaction time into calculations. A driver traveling at 25 m/s takes 1.0 second to react before braking at a deceleration of 3.0 m/s², ultimately stopping 5.0 meters from a hazard. The total time to stop is calculated as 9.3 seconds, which includes both the reaction time and the time taken to decelerate. The kinematic equations are emphasized as essential tools for determining displacement and time in such scenarios.

PREREQUISITES
  • Understanding of kinematic equations
  • Knowledge of initial velocity and acceleration concepts
  • Familiarity with the concept of reaction time in physics
  • Ability to perform basic algebraic calculations
NEXT STEPS
  • Study the kinematic equation for displacement: \(d = v_i t + \frac{1}{2} a t^2\)
  • Learn how to calculate stopping distance using initial velocity and deceleration
  • Explore the effects of reaction time on stopping distances in various scenarios
  • Investigate real-world applications of kinematics in automotive safety
USEFUL FOR

Students studying physics, particularly those focusing on kinematics, as well as educators and anyone interested in understanding the impact of reaction time on motion and safety in driving scenarios.

stphillips
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Homework Statement


1) A driver is traveling at 25m/s when she spots a sign that reads "Bridge Out Ahead". It takes her 1.0 s to react and begin breaking. The car slows down at a rate of 3.0 m/s2. Luckily, she stops 5.0m short of the washed-out bridge.
(a) How much time was required to stop the car when she spotted the sign?
(b) How far was the driver from the bridge when she first noticed the sign(keep in mind her reaction time)

Homework Equations



The Attempt at a Solution


25 m/s / 3m/s2 = 8.3seconds + 1 second (reaction time) = 9.3 seconds.
b)
 
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For (b) there is one of the four kinematics that is particularly useful for this problem and many others being that you are given an initial velocity, an acceleration, a final distance, and you just found the time coordinate from completing (a). Which of the kinematics incorporates these all of these variables as well as pertaining to a displacement? That ought to get you in the right direction.

Joe
 

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