Acceleration Question* * (Physics 11)

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SUMMARY

The discussion revolves around a physics problem involving a car's braking distance and acceleration. The driver initially travels at 90.0 km/h and takes 0.75 seconds to react before applying brakes with an average acceleration of -10.0 m/s². To determine if the car hits the barrier 40.0 m ahead, the distance covered during the reaction time must be calculated, followed by applying the equations of motion to ascertain the stopping distance. The solution requires using the kinematic equations to analyze the motion before and during braking.

PREREQUISITES
  • Understanding of kinematic equations in physics
  • Knowledge of acceleration and its effects on motion
  • Ability to convert units (e.g., km/h to m/s)
  • Familiarity with basic concepts of distance, speed, and time
NEXT STEPS
  • Study the kinematic equations of motion, particularly the equations relating distance, speed, and acceleration
  • Learn how to convert speeds from kilometers per hour to meters per second
  • Practice problems involving reaction time and braking distance calculations
  • Explore graphical representations of motion to enhance understanding of physics concepts
USEFUL FOR

This discussion is beneficial for high school physics students, educators teaching motion concepts, and anyone preparing for physics exams that involve kinematics and acceleration scenarios.

wonton1017
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Acceleration Question*URGENT* (Physics 11)

Okay well i have a test tomorrow and this is a question that was on my quiz, and i didnt know how to do this:

Homework Statement


1. A driver of a car going 90.0km/h suddenly sees a barrier 40.0m ahead. It takes the driver 0.75s before she applies the brakes, and the average acceleration during braking is -10.0m/s^2.
a. determine if the car hits the barrier (need to know how you got it, please tell me which equation and why :/ i know this involves 2 steps.)
b. what is the maximum speed at which the car could be moving and not hit the barrier 40.0m ahead? assume acceleration doesn't change.


Homework Equations





The Attempt at a Solution


I haven't a clue, need help >.<
 
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During the 0.75 seconds the driver is moving with a constant speed. Use the speed and time to calculate the distance covered in this time interval. The distance to the barrier is now reduced by this amount. That is

[tex]d_{remain} = 40.0 - d_{react}[/tex]
 
and then, apply the equation of motion (s-u-v-a-t equations) to check what distance it takes to stop. (you know u, v, and a.)
Drawing a rough sketch always helps in Physics. Even in such a simple question.
 

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