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Champ07
Sep9-07, 12:01 PM
1. The problem statement, all variables and given/known data
For each of the following situations below circle the appropriate signs for each quantity listed.
Assume east is + and west is -

(see photo below)


2. Relevant equations
None I believe


3. The attempt at a solution
I did it but I'm not really sure if I'm right. Can someone tell me if its all right or how you determine the right answers
http://img338.imageshack.us/img338/4234/physicshb9.jpg

Doc Al
Sep9-07, 12:18 PM
Only b is correct. Explain your reasoning for your answers. For example, what determines whether displacement is + or -?

Champ07
Sep9-07, 12:22 PM
Well to be honest I'm really not sure. This is my first week of Physics (AP) and I've been really confused about the class so far.

For A and C which parts were wrong?

For A:
Displacement + because as you move away from 0 your displacement from the original increases doesn't it?
Velocity + because your moving west so its +
Acceleration your speeding up so its +
C
If you start east and move west isn't it then negative?

I'm really not sure. If you can could you please explain the right answers to me it would be a huge help

Doc Al
Sep9-07, 12:30 PM
For A:
Displacement + because as you move away from 0 your displacement from the original increases doesn't it?
Signs--which indicate direction--count. Note the instructions that east is + and west is -. If it is east of the origin, its displacement is +.

Velocity + because your moving west so its +
Again, direction and signs count.


Acceleration your speeding up so its +
Speeding up in what direction?
C
If you start east and move west isn't it then negative?
Isn't what negative? "Moving west" describes velocity, so velocity would be negative. But what about displacement and acceleration?

Champ07
Sep9-07, 12:37 PM
Ok then for A taking direction into account since west is - then displacement, velocity and acceleration would all be - wouldn't they?

For C acceleration would be + and displacement + because your position is changing.

Is that correct?

Doc Al
Sep9-07, 12:55 PM
All good!

Champ07
Sep9-07, 01:18 PM
Thank you very much