Some conceptual collision/energy stuff

  • Thread starter lollol
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In summary: In other words, at negative total energy, some parts of the system are in a state of "static equilibrium" with the surroundings, rather than "free" (i.e. moving). 2) It simply asked if an inelastic or an elastic collision would cause more damage to you?If the collision is inelastic, then the momentum will be distributed equally and there won't be any damage. If the collision is elastic, then the momentum will be concentrated in one area and there will be damage.
  • #1
lollol
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1) I was thinking about the definitions of KE and PE... can't the values KE and PE only ever be positive...? so

ME = KE + PE

Can total mechanical energy ever be negative? I'm thinking it cannot

2) also let's say you're in a car and you collide with another car... I'm trying to compare the impact of an inelelastic vs. elastic collision.. which would actually cause more damage to you? if the cars stick... or if they rebound?

I'm really clueless on this
 
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  • #2
1] Mechanical energy is somewhat relative to a reference point. Like, if you consider that a level 1000km above you has potential energy 0, then your P.E would be hugely negative and if you are at say.. rest.. your KE will be '0' and mechanical energy will hence be negative.

2] It doesn't really matter what kind of collision you are in but what really matters is how your vehicle gives into the stress. The type of collisions that u mention controll/predict only the final velocities and trajectories of the bodies colliding. For safety data, you need to know the yield strength and similar parameters for your vehicle.
 
  • #3
This is basic, basic high school physics.. and I was going through the textbook, these were just conceptual questions to think about

1) It just asked if mechanical energy can be negative

2) It simply asked if an inelastic or an elastic collision would cause more damage

you're thinking too much IMO. There is a definitive answer... this is basic high school level physics
 
  • #4
With an elastic collision we can think of the momentum being distributed equally, atomically. If an elastic impact yielded .00000001 Newtons per atom, we could not make the same generalization about an inelastic collision.
 
  • #5
lollol said:
This is basic, basic high school physics.. and I was going through the textbook, these were just conceptual questions to think about

1) It just asked if mechanical energy can be negative

Yes, it can. For two reasons: one is a bit silly, and comes from the fact that you can define your "0" for potential energy just anywhere: potential energy is defined up to an arbitrary constant. For instance, the potential energy in a uniform gravity field with acceleration g of a mass m is usually written as: V = m x g x h, where h is the "height" (but measured from where ?). But you can just as well write: V = m x g x h + C, where C is an arbitrary constant. You can even see this C as meaning that you took another reference point for your "h".

So total mechanical energy, being KE + V, is also defined up to an arbitrary constant (the one in C). So you can give it any value, positive or negative, to your liking.

But another reason is "more serious". By convention, one usually takes potential energy to be 0 at "infinite separation". IF you take this convention, then negative total energy means that you have a "bound state": that not all the particles/constituents of your system can get arbitrarily far away from each other, but that at least some need to stay "together".
 

Related to Some conceptual collision/energy stuff

1. What is a conceptual collision?

A conceptual collision is a term used to describe the interaction between two or more ideas or concepts that seem to contradict or conflict with one another. It often occurs when trying to understand a complex scientific concept.

2. How does energy play a role in conceptual collisions?

Energy is a fundamental concept in science and is often involved in conceptual collisions. This is because energy can take on different forms and can be transferred or transformed between different systems, leading to conflicting ideas or explanations.

3. Can conceptual collisions be resolved?

Yes, conceptual collisions can be resolved through further research and experimentation. By gathering more data and evidence, scientists can better understand the underlying principles and reconcile conflicting ideas.

4. What are some examples of conceptual collisions in science?

One example could be the wave-particle duality of light, where light exhibits properties of both waves and particles. Another example could be the theory of relativity, which clashes with classical mechanics at high speeds and in extreme gravitational fields.

5. How can conceptual collisions benefit scientific progress?

Conceptual collisions can lead to new discoveries and advancements in science. By challenging existing theories and ideas, scientists can uncover new perspectives and approaches, ultimately leading to a deeper understanding of the natural world.

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