How Close Does the Truck Get to the Car During Acceleration?

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Homework Help Overview

The problem involves a truck approaching a car that is stopped at a red light. The truck travels at a constant speed while the car accelerates from rest when the light turns green. The objective is to determine how close the truck gets to the car during this acceleration phase.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster expresses uncertainty about which equations to use and whether to set the positions of both vehicles equal to each other. Some participants suggest that the closest distance occurs when their velocities are equal, while others propose expressing the distance as a function to find a minimum distance.

Discussion Status

There are multiple lines of reasoning being explored, with some participants offering insights into the relationship between the velocities of the truck and the car. The discussion reflects a mix of interpretations regarding the best approach to solve the problem.

Contextual Notes

The original poster is navigating the problem without clear direction on the equations or methods to apply, indicating a potential gap in foundational understanding of the concepts involved.

Amel
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Homework Statement



To save fuel, some truck drivers try to maintain a constant speed when possible. A truck traveling at 92.0 km/hr approaches a car stopped at the red light. When the truck is 121.2 meters from the car the light turns green and the car immediately begins to accelerate at 2.80 m/s2 to a final speed of 125.0 km/hr. How close does the truck come to the car assuming the truck does not slow down?

and How far from the stop light has the car traveled when the truck reaches its closest distance?


So what do I need to do here, I am not even sure which equations to use. Do I need to set the x of both equal to each other?

Can some one please walk me through this problem.
 
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never mind figured it out, they are closest to each other when their velocity is the same. so you set the V equal to each other.
 
Amel said:
never mind figured it out, they are closest to each other when their velocity is the same. so you set the V equal to each other.

Can you express the distance between them as a function? Then it would be possible to find a minimum, which would be the closest distance.
 
kbaumen said:
Can you express the distance between them as a function? Then it would be possible to find a minimum, which would be the closest distance.

Works too, but the OP's approach is much easier, albeit less straightforward. Good job, OP!
 

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