Is the outcome of a collision determined by the observer's perspective?

In summary, two objects, a and b, traveling towards each other at 100 m/s, are observed by three observers, OA, OB, and OC. From OA's perspective, b collides with a at 100 m/s, while from OB's perspective, a collides with b at 100 m/s. From OC's perspective, both objects collide at 50 m/s each. However, the result of the collision would be the same in all three frames, as the strength of the impact is determined by the velocity difference of the objects before impact, which is the same in all three frames. This demonstrates the principle of relativity in classical mechanics, where the laws of physics are the same in all inertial reference frames
  • #1
Flexo
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Consider two objects, a and b, traveling toward each other at, say, 100 m/s.
There are three observers, OA, OB, and OC. With respect to OA, a is stationary. With respect to OB, b is stationary. From OC's point of view, both objects are approaching each other at 50 m/s.
From OA's perspective, b collides with a at 100 m/s. From OB's perspective, the opposite occurs. From OC's perspective, both objects collide at 50 m/s each.

It seems to me that the result of each of these scenarios would be different. OA would see a go backwards, OB would see b do so, and OC would see both cease motion.
Only one of these events would actually occur.
Does that not imply that one of the observers had a "correct" viewpoint?

Additionally, it seems to me that a collision between two cars traveling at 50 m/s toward each other will have different results than one car traveling toward a stationary one at 100 m/s. Is that correct?
 
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  • #2
Flexo said:
It seems to me that the result of each of these scenarios would be different. OA would see a go backwards, OB would see b do so, and OC would see both cease motion.
Only one of these events would actually occur.
Does that not imply that one of the observers had a "correct" viewpoint?
No. The speed and direction that something moves clearly depends on who is doing the observing. But it has no physical consequence--you can easily transform measurements from one frame to another. (This is the principle of relativity in classical mechanics.)
Additionally, it seems to me that a collision between two cars traveling at 50 m/s toward each other will have different results than one car traveling toward a stationary one at 100 m/s. Is that correct?
No. Let's keep it simple. Say the two cars are sliding towards each other on a frictionless surface (ice, for example) so that no other forces are involved. Whether one car is at rest and the other is moving at 100 m/s, or both move at 50 m/s is simply a matter of reference frame. Pick the reference frame that is most useful--but any will do.
 
  • #3
Doc Al said:
No. The speed and direction that something moves clearly depends on who is doing the observing. But it has no physical consequence--you can easily transform measurements from one frame to another. (This is the principle of relativity in classical mechanics.)

No. Let's keep it simple. Say the two cars are sliding towards each other on a frictionless surface (ice, for example) so that no other forces are involved. Whether one car is at rest and the other is moving at 100 m/s, or both move at 50 m/s is simply a matter of reference frame. Pick the reference frame that is most useful--but any will do.

I suppose I'm just visualizing it poorly. Thanks, though.
 
  • #4
Flexo:
The strength of the impact is directly related to the velocity DIFFERENCE of the two objects directly before impact.

Thus, in two distinct inertial frames, although they assign different velocities to the two object, they'll calculate the same velocity difference, yielding the same prediction as to what happens in the collision.
 

FAQ: Is the outcome of a collision determined by the observer's perspective?

What is the concept of relativity in collisions?

The concept of relativity in collisions refers to the idea that the outcome of a collision between two objects is dependent on the relative velocity and direction of the objects involved. This means that the same collision can have different outcomes depending on the frame of reference from which it is observed.

How does the theory of relativity impact collisions?

The theory of relativity, developed by Albert Einstein, states that the laws of physics are the same for all observers in uniform motion. This means that the effects of motion and velocity must be taken into account when analyzing collisions, as the outcome can vary depending on the frame of reference.

Are all collisions relative?

Yes, all collisions are relative. This means that the outcome of a collision is dependent on the relative velocity and direction of the objects involved, as well as the frame of reference from which it is observed.

How do we calculate the outcome of a collision in a specific frame of reference?

To calculate the outcome of a collision in a specific frame of reference, we must consider the velocity and direction of the objects involved, as well as the laws of physics that govern the interaction between them. This can be done using mathematical equations and principles such as momentum, energy, and conservation laws.

Can the outcome of a collision be predicted in all frames of reference?

No, the outcome of a collision cannot be predicted in all frames of reference. This is because the laws of physics may appear different in different frames of reference, and the relative velocity and direction of the objects involved can also affect the outcome. However, by using the principles of relativity, we can accurately predict and explain the outcome of a collision in a specific frame of reference.

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