Undergrad Can we add two vectors that are not acting simultaneously using vector addition?

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The discussion centers on whether two forces applied sequentially can be added using vector addition. It is clarified that vector addition is applicable only for forces acting simultaneously, as the direction and timing of forces significantly impact the resultant force. When forces are applied one after the other, the resulting motion can differ based on the time elapsed and the object's state at each application. Examples are provided to illustrate that while displacement vectors can be added sequentially, force vectors cannot be treated the same way. Overall, the consensus is that the question lacks validity in the context of force application.
prashant singh
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Suppose if I applied a 4N force and then 2N force on an object , what will be total force. Note I didn't said simoultaneously, I mean one after the other, then what will be the total force , I think 6N , i know about vector sum and etc.. but I think this question doesn't makes any sense. What's your opinion. vector addition and vector algebra is applied for simoultaneous force(vectors).
 
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What's the direction of the forces?
 
No. A time sequence of forces is not equivalent to the sum of those forces at a single time. If you graphed the acceleration and associated velocities over time, you would see that you will not get the same result from the two cases.
 
I think this question doesn't makes any sense because vector algebra is applied for simooultaneous vectors(here force). I think direction doesn't matters but u can take both in same direction.
 
prashant singh said:
I think this question doesn't makes any sense because vector algebra is applied for simooultaneous vectors(here force). I think direction doesn't matters but u can take both in same direction.
That depends on how you are using the vectors. If a person moves from A to B and then from B to C, you can add two motion vectors AB and BC to get the total motion vector AC. But force doesn't work that way.
 
I think this question doesn't makes any sense because vector algebra is applied for simooultaneous vectors(here force). I think direction doesn't matters but u can take both in same direction.
 
prashant singh said:
Suppose if I applied a 4N force and then 2N force on an object , what will be total force. Note I didn't said simoultaneously, I mean one after the other, then what will be the total force , I think 6N
The magnitudes of the forces add like this only if the forces are acting in the same direction.

prashant singh said:
I think direction doesn't matters but u can take both in same direction.
Of course the direction matters.

Also, "textspeak" such as "u" for "you" is not allowed at this site.
 
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Okk sorry for using u
Mark44 said:
The magnitudes of the forces add like this only if the forces are acting in the same direction.

Of course the direction matters.

Also, "textspeak" such as "u" for "you" is not allowed at this site.
 
Can we add two vectors which are not acting simoultaneously by the vector law of addition.
FactChecker said:
That depends on how you are using the vectors. If a person moves from A to B and then from B to C, you can add two motion vectors AB and BC to get the total motion vector AC. But force doesn't work that way.
 
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  • #10
prashant singh said:
Can we add two vectors which are not acting simoultaneously by the vector law of addition.
I don't think that makes sense. If you have some object that is moving along a path, and you apply a force to it, that force could cause the object to change direction (or not, all depending on the direction of the force and the direction the object is moving). If later a different force is applied, then that could cause a different resulting direction for the object. To the best of my knowledge, you don't add vectors that aren't acting simultaneously (simoultaneously is not a word).

Also, if the two forces are applied at different times (i.e., not simultaneously), how much time elapses between the times of the two forces? One second, one hour, one week, ten years?
 
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  • #11
Exactly
Mark44 said:
I don't think that makes sense. If you have some object that is moving along a path, and you apply a force to it, that force could cause the object to change direction (or not, all depending on the direction of the force and the direction the object is moving). If later a different force is applied, then that could cause a different resulting direction for the object. To the best of my knowledge, you don't add vectors that aren't acting simultaneously (simoultaneously is not a word).

Also, if the two forces are applied at different times (i.e., not simultaneously), how much time elapses between the times of the two forces? One second, one hour, one week, ten years?
 
  • #12
prashant singh said:
Can we add two vectors which are not acting simoultaneously by the vector law of addition.
You can if it makes sense for the context of the situation . For instance a displacement of 3km due north followed by a displacement of 4km due east. Those displacement vectors can be added to give the overall displacement.

This sort of vector addition does not make sense if one force is followed by a second force.
 
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