Ridiculously simple acceleration and velocity vectors, but I can't get them

[soggybread]

Ridiculously simple acceleration and velocity vectors, but I can't get them...

We're supposed to answer a series of questions based on this diagram, but I am so confused by the answers.

Homework Statement

A car travels at constant speed along the curved path shown in the figure below. Five possible vectors are also shown in the figure; the letter E represents the zero vector.

These are the 3 questions (along with the correct answers from the key):

1. Which vector best represents the car's acceleration at point 1?
answer: E

2. Which vector best represents the car's acceleration at point 2?
answer: D

3. Which vector best represents the car's acceleration at point 3?
answer: A

I don't get these answers at all, first the question tells me the car is traveling at a constant speed, (which I answered in question 1, E) Then it says it's D for question 2, then it's A for question 3? I don't get how these vectors connect together at all, and it's completely stumped me.

Thanks.

 

[Galileo's Ghost]

Remember, velocity is a vector quantity. It has magnitude and direction. If direction is changing, then the velocity is changing. If the velocity is changing, then there must be non-zero acceleration.

The car is experiencing centripetal acceleration at 2 and 3. Centripetal acceleration is always directed toward the center of the turn, at a right angle to the direction of motion.