Car Acceleration homework questions

[aquapod17]

Homework Statement

Which of the following is true?
a. None of these answers are correct.
b. If a car is traveling eastward, its acceleration is eastward.
c. A particle with constant acceleration can never stop and stay stopped.
d. If a car is slowing down, its acceleration must be negative.

Homework Equations

a = v/t

The Attempt at a Solution

I'm not sure what the answer is. I'm thinking it's a, but I'm not really sure.

 

[nicksauce]

For a let's try to think of a simple analogy.
a) If a man is jumping upward, his acceleration is upward.
Can you see why this isn't true?

b) A little ambiguous, but can you think of a way a particle can have a constant acceleration, and not be moving?

c) Again, a little ambiguous... but I just picture everything here going in the positive x direction. Just think about how velocity and acceleration relate. acceleration = change in speed divided by change in time? If change in speed is negative, what is acceleration?

 

[tornzaer]

I'd say it's "d". Slowing down is pretty much negative acceleration.

b: The car might be going east, but it might be traveling at a constant velocity.
c: Outside force to stop it.