Multiple Choice Kinematics Question

[Champ07]

Kinematics Question (Speed, velocity and acceleration)

Homework Statement

For each of the following situations below circle the appropriate signs for each quantity listed.
Assume east is + and west is -

(see photo below)

Homework Equations

None I believe

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]

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

 

[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

 

[Doc Al]

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]

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]

All good!

 

[Champ07]

Thank you very much