Basic motion stuffs, time and velociton

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Discussion Overview

The discussion revolves around a problem involving the motion of two particles with different velocities and an initial distance between them. Participants are attempting to determine the time at which the two particles will meet, considering their respective speeds and the distance separating them. The scope includes mathematical reasoning and problem-solving related to basic motion concepts.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant describes the problem of two particles, A and B, with velocities of 80 km/h and 100 km/h respectively, and an initial distance of 350 km between them.
  • Another participant suggests using the equations of motion to set the distances equal to each other and solve for time.
  • A different participant simplifies the problem using the formula for distance as rate times time, proposing to express the distances in terms of a variable and solve for time.
  • One participant expresses confusion about whether to add the distances and seeks clarification on how to set up the equations correctly.
  • A later reply introduces the concept of relative velocity, suggesting to consider one particle as stationary and calculate the relative speed to simplify the problem.

Areas of Agreement / Disagreement

Participants present various approaches to solving the problem, and there is no consensus on a single method or solution. Confusion exists regarding the setup of the equations, indicating differing interpretations of the problem.

Contextual Notes

Some participants' responses depend on assumptions about the setup of the equations and the interpretation of distances and velocities. There are unresolved mathematical steps in the proposed solutions.

k3l
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Basic motion stuffs, time and velociton :(

hi
oh my gosh... i can't believe i forgotten how to do this...
i have to work out the time when will the two particles meet... where one particle (A) is traveling at a velocity of 80km/h, and (B) is traveling with a velocity of 100km/h while (B) is 350km behind (A)
(assume they are traveling toward the same directions)

thx
 
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[tex]s_a = s_b[/tex]
[tex]s_a = s_0 + v_a * t[/tex]
[tex]s_b = v_b * t[/tex]

Insert both in first equation and calculate t.
 
Basic algebra.

Distance=rate x time

D1=x
D2=x+350
so for the equation distance = rate x time just plug in x and x+350 as your distance, use t for time
since x is the same value, you can combine the two and solve for t.
 
I'm a bit confused, do you add the 2 distances?
[tex]x+x+350=100 \\ or \\ 80? *t?[/tex]
Maybe I'm stupid but I'm confused...
 
use relative time frames. Take the moving particles frame that is behind the other particle, subtract the other cars speed and no consider that the other particle is stationary.

[tex]V_{slower\ particle} = 80km/h[/tex]
[tex]V_{faster\ particle} = 100km/h[/tex]
[tex]V_{faster\ particle\ relative\ to\ slower\ one} = 100km/h - 80km/h = 20km/h[/tex]

now your system becomes linear.

use:

[tex]d = Vt[/tex]

you should know what to sub in where.

Regards,

Nenad
 

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