Distance traveled during a head on collision

[haruspex]

1500*(20)+2400*(-12.5) = (1500+2400)*0

Makes it look like he is equating 20 - 12.5 with 0

Sorry, I still can't see how you can read it that way. Are you suggesting some interpretation of the asterisks other than multiplication?

 

[phinds]

Sorry, I still can't see how you can read it that way. Are you suggesting some interpretation of the asterisks other than multiplication?

See post #29 for someone who had an immediate response identical to mine.

 

[haruspex]

See post #29 for someone who had an immediate response identical to mine.

Well, I can't see how that fits with what you wrote in post #30, and jbriggs' "physics" interpretation is how I read it. Mr. Krock took the equation m₁v_1i+m₂v_2i=(m₁+m₂)v_f, plugged in the known values and found that v_f must be 0. He then posted that fact in the form of a solved equation. I'm sure it was not intended to represent the logic by which he arrived at the result. As a way of illustrating where he was up to, I have no problem with it.

 

[phinds]

Well, I can't see how that fits with what you wrote in post #30,

You're right. Post #30 was an incorrect way to express my dismay at his intermediate result.

I'm sure it was not intended to represent the logic by which he arrived at the result.

Well, I'm not a mind reader. I was commenting on what he posted, not what he meant (although actually, I addressed that as well).

As a way of illustrating where he was up to, I have no problem with it.

Well, I do. Let's agree to disagree.

 

[haruspex]

You're right. Post #30 was an incorrect way to express my dismay at his intermediate result.

Well, I'm not a mind reader. I was commenting on what he posted, not what he meant (although actually, I addressed that as well).

Well, I do. Let's agree to disagree.

Ok, all good.

 

[NickAtNight]

It would help if we could get him to write the two equations.
To list the number of unknowns
To determine if there are enough equations to solve for the unknowns
To rearrange the equations to solve for the unknowns

Then to give the results for the three conditions 1) fully elastic. 2) inelastic 3) partially elastic.

Then to answer the question two ways. 1) for what was asked - distance travelled. Which is not knowable since no stopping forces were provided.

2) for what they probably wanted to ask - vehicle velocities.

 

[haruspex]

It would help if we could get him to write the two equations.
To list the number of unknowns
To determine if there are enough equations to solve for the unknowns
To rearrange the equations to solve for the unknowns

Then to give the results for the three conditions 1) fully elastic. 2) inelastic 3) partially elastic.

Then to answer the question two ways. 1) for what was asked - distance travelled. Which is not knowable since no stopping forces were provided.

2) for what they probably wanted to ask - vehicle velocities.

No progress can be made at all until we are clear what is meant by the distance a vehicle travels during a collision. See post #25.