How Long Will It Take for the Car to Collide with the Truck?

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Homework Help Overview

The discussion revolves around a scenario involving a car and a truck, where the car is initially 25 meters behind the truck that has suddenly braked. The car's initial speed is given as 110 km/h, and it is decelerating at a rate of -6.5 m/s². Participants are exploring how long it will take for the car to collide with the truck, or if it will collide at all, and what changes to the deceleration would be necessary for a collision to occur.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are discussing the initial conditions, including the car's speed and deceleration. There are questions about the time it takes for the car to reach the truck and the distance covered during deceleration. Some participants are also considering what adjustments to the deceleration would be needed for a collision to occur.

Discussion Status

The discussion is ongoing, with participants questioning the initial calculations and assumptions. Some guidance has been offered regarding the need to compute the distance covered by the car during deceleration and its relation to the 25 meters separating it from the truck. There is no explicit consensus yet, as various interpretations and calculations are being explored.

Contextual Notes

Participants are working under the constraints of the problem as posed, including the initial conditions of speed and distance, and the imposed deceleration rate. There is an emphasis on understanding the implications of these parameters on the outcome of the scenario.

wangwang2626
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Ok so the car is 25 m behind a truck which suddenly braked. I put it as decelerating at -6.5 m/s it was traveling at 110km/h . I would like to know how long it takes to collide with the truck , and if it dosent what would I have to change the deceleration to be so that it does collide with the truck?
What I did was
v=vo+at
t=(v-vo)/a
t=30.5556/(-6.5)
but that's obviously wrong
I don't know what to do next
or what other formula to use
 
Last edited:
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How fast was the car going and how fast is it decelerating, starting with how long after the truck is decelerating?
 
the car was traveling at 110km/h when they noticed that the truck was not moving , it was 25 meters behind , I said it was decelerating at 6.5 m/s so how long would it take till it got to the truck and at what speed would it hit the truck. If the car does not reach the truck can you please suggest a different deceleration?
 
In the absence of the truck, how much distance is covered by the car from the moment it starts to decelerate until its speed = 0? Is that distance < or > 25m? (Hint: you first need to compute the time to decelerate to zero, which you have already done except for the wrong sign).

When you get this part we can continue with the second part of the question.
 

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