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rasofia77

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**1. Problem Statement:**What is the velocity of John relative the bus in each of the following situations:

A) John is sitting on the street and the bus is moving at 30m/s toward him

B)John is sitting in his car traveling North at 25m/s toward a stationary bus?

C)John is sitting in his car traveling North at 35 m/s and the bus is moving 15 m/s toward him?

**2. Relevant Equations:**oVe=oVm+mVe

**3. Work on the Solution:**So I'm struggling a bit with relative motion, but these are my thought processess

A)Ok, so John is sitting and the bus is coming at him with a velocity of 30...Since it's asking for 'velocity of John relative the bus'...I see it in the bus's perspective, John would look like he's going toward it..therefore he would look like he's going 30 m/s south, which is -30 m/s (BUT, the answer, as my teacher let me know, is positive 30, so 30 north...why is that?)

B) Ok now, the bus, again sees John traveling to it at 25 m/s, so again I would think that would be South since to the bus it looks that way..so -25m/s...but the answer is positive, so north.

Actually, I used this equation: jVb=jVe + eVj ... 25-0=25 ...so I know why it's positive in terms of the equation, but I want to know how logically..

C)For this one, I think I just used the equation, so johnVearth=35 and busVearth=-15. Therefore johnVbus= johnVearth + earthVbus ---> jVb= (35)+(15) ...since eVb is opposite of bVe...so that's 50m/s. And that's the correct answer.

Basically, my real question here is..how does all this make sense logically..not numerically/factually...but how can I see it in a way that it makes sense- the directions and all. And for the first one especially, why North, not South? Shouldn't it be relative to the bus, the way the bus sees it?

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