What Is the Minimum Stopping Distance for a Car Traveling at 50 m/s?

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Homework Help Overview

The discussion revolves around calculating the minimum stopping distance for a car traveling at a speed of 50 m/s, building on a previous example where a car traveling at 30 m/s had a stopping distance of 60 m, including the driver's reaction time.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to relate the stopping distances at different speeds and are questioning how to incorporate the driver's reaction time into their calculations. There is discussion about whether to consider acceleration as zero and how to apply the given formula for stopping distance.

Discussion Status

Some participants are providing insights on how to account for the reaction time and the distance traveled during that time. Others are exploring the implications of the initial stopping distance and how it affects the calculations for the higher speed. There is a mix of understanding and confusion among participants regarding the application of the concepts.

Contextual Notes

Participants are working under the constraints of using the initial stopping distance as a reference point and are trying to derive the necessary values for acceleration and distance without complete clarity on how to integrate the reaction time into their equations.

jo3jo3520
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The minimum stopping distance for a car traveling at a speed of 30 m/s is 60 m, including the distance traveled during the driver's reaction time of 0.50 s.

(a) What is the minimum stopping distance for the same car traveling at a speed of 50 m/s?


Vf^2 = Vi^2 +2ax


So i would be solving for X here right? so the car is not accelerating do i plug in 0 for a?

This is what i have so far

0=50^2+2(a)(x) where does the .5 reaction time come into play?
 
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jo3jo3520 said:
The minimum stopping distance for a car traveling at a speed of 30 m/s is 60 m, including the distance traveled during the driver's reaction time of 0.50 s.

(a) What is the minimum stopping distance for the same car traveling at a speed of 50 m/s?


Vf^2 = Vi^2 +2ax


So i would be solving for X here right? so the car is not accelerating do i plug in 0 for a?

This is what i have so far

0=50^2+2(a)(x) where does the .5 reaction time come into play?

You're right that the .5sec reaction time needs to be accounted for.

But you need to first account for it from the first measurements.

The Total distance traveled to stopping included .5*(30m/s). Then the total change in velocity occurred over that smaller distance - not including reaction time.

Now for the 50m/s case how long to stop if you use the deceleration from the first measured stop? From that distance you then need to add the (50m/s)*.5sec to get your total distance.
 
ok so .5*30 = 15 but I am confused on what to do with that? you said "Then the total change in velocity occurred over that smaller distance - not including reaction time." ?
 
am i supposed to do 30/15? and where in the equation do i plug this number in?
 
help anyone?
 
jo3jo3520 said:
ok so .5*30 = 15 but I am confused on what to do with that? you said "Then the total change in velocity occurred over that smaller distance - not including reaction time." ?

So the car deceleration alone was only over 45m and not 60m then wasn't it? Now figure the deceleration performance of just the car.

You have Velocity and distance, so find acceleration "a" that gives you that deceleration over 45m.
 
Either I am just really dumb or not understanding but i give up. thank you for your help
 

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