Solving Momentum & Force for Car & Truck Collision

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Homework Help Overview

The discussion revolves around a collision scenario involving a car and a truck, focusing on the relationship between their forces and the time taken for each vehicle to come to a halt. The original poster presents a situation where the momentum of both vehicles is equal, with the car having a velocity five times that of the truck and the truck's mass being five times that of the car. The inquiry seeks to mathematically demonstrate the equality of forces exerted by each vehicle during the collision.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to use a specific equation relating the forces and times of the vehicles during the collision. Some participants question the interpretation of "coming to a halt" and suggest considering the effects of deformation during the collision. Others propose that the time of contact is the same for both vehicles, implying a straightforward application of Newton's third law.

Discussion Status

The discussion is ongoing, with various interpretations being explored. Some participants have offered insights into the implications of the collision dynamics, while others have raised questions about the assumptions made regarding the vehicles' behavior during the impact.

Contextual Notes

There is a lack of clarity regarding the definition of "coming to a halt" in the context of the collision, as well as the effects of deformation on the vehicles involved. The original poster's approach relies on specific conditions that may not fully account for the complexities of real-world collisions.

faiziqb12
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i have two bodies and their momentum is same ...
say i have a truck and a car and they collide ...
the velocity of car is five times the velocity of truck...
and the mass of the truck is five times the mass of the car...
so my question is how to mathametically prove that the force of the car on the truck will be equal to the force of the truck on the car...


actually i have to find that the time in which the car comes in halt is equal to the time in which the truck comes to halt...

so , please help me with the problem in classic text above , then my problem is solved....
i am using the equation fct * tc = ftc * tt
where tc and tt is the time in which the car and truck come to halt respectively

and if u have any other method of soving my actual question please post!

thanks in advance
 
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Well, the time they are in contact is the same for both, right? So tc = tt and there you are ! You have proven Newton's third law :wink:
 
thanks
 
BvU said:
Well, the time they are in contact is the same for both, right? So tc = tt and there you are ! You have proven Newton's third law :wink:
Not quite that simple.
Since the collision takes time, one or both vehicles must be deformed. So what is meant by a vehicle coming to a halt? The only reasonable interpretation I can think of is to consider the mass centre of the vehicle (though that is changing in relation to the architecture of the vehicle as the deformation occurs).
We can model this as point masses with massless imperfectly elastic springs attached, colliding spring to spring. How will you prove that each mass comes to rest, momentarily at least, at the same instant?
 

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