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Relative vectors - how do you determine?

  • Thread starter Trooper100
  • Start date
  • #1
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1. The problem statement

I find it sometimes difficult to come up with the equation relevant to the question. If any one has any tips, your help is appreciated.

2. Relevant example

For example:

A passenger climbs aboard a northbound bus and walks toward the back at a rate of 1.8m/s. The bus starts off up the street at 9.2m/s. What velocity will the passenger appear to be walking relative to:

A) a person who is walking 2.1 m/s south along the sidewalk
B) a person who is walking 2.1 m/s north along the sidewalk

The Attempt at a Solution



Let p = passenger in the bus
b = Bus
g = guy who is walking

My attempt: a) Vpg = Vpb + Vbg is this correct? why or why not? thanks.
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
25,832
249
Hi Trooper100! :smile:

(try using the X2 tag just above the Reply box :wink:)
Let p = passenger in the bus
b = Bus
g = guy who is walking

My attempt: a) Vpg = Vpb + Vbg is this correct? why or why not? thanks.
Yes, that's correct, because you've put the letters in the right order … pg = pb + bg. :smile:

(For example , if you wanted to know Vpb,

you would write Vpb = Vpg + Vgb = Vpg - Vbg :wink:)
 
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