# Kinematics Question

1. Sep 9, 2007

### Champ07

Kinematics Question (Speed, velocity and acceleration)

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

Last edited: Sep 9, 2007
2. Sep 9, 2007

### Staff: Mentor

Only b is correct. Explain your reasoning for your answers. For example, what determines whether displacement is + or -?

3. Sep 9, 2007

### Champ07

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

4. Sep 9, 2007

### Staff: Mentor

Signs--which indicate direction--count. Note the instructions that east is + and west is -. If it is east of the origin, its displacement is +.

Again, direction and signs count.

Speeding up in what direction?
Isn't what negative? "Moving west" describes velocity, so velocity would be negative. But what about displacement and acceleration?

5. Sep 9, 2007

### Champ07

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?

6. Sep 9, 2007

All good!

7. Sep 9, 2007

### Champ07

Thank you very much

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