Isn't acceleration a constant?

1. Aug 23, 2007

chaotixmonjuish

The position of a particle as a function of time (in s) is given by C1 + C2t + C3t2. Let C1 = 12.1 m, C2 = 14.9 m/s and C3 = -0.38 m/s2.

I was able to solve the first question, which was asking for the velocity at T=11.0 seconds. However, I don't understand how to solve this part of the question:

What is the particle's acceleration at time t = 11.0 s?

I thought acceleration was a constant? I tried punching the constant into Lon-capa, but it said the answer was wrong.

2. Aug 23, 2007

learningphysics

Yes, acceleration turns out to be constant. What number did you get for the acceleration?

3. Aug 23, 2007

chaotixmonjuish

I got something like -.76 for my acceleration. However Lon-capa rejects it.

4. Aug 23, 2007

learningphysics

Yeah, -0.76 is the right answer.

Is the question exactly as you posted it?

5. Aug 23, 2007

chaotixmonjuish

That's is the question.

6. Aug 23, 2007

learningphysics

Hmmm... I'm not familiar with Lon-Capa... maybe something about the way you entered it? Did you enter it as -0.76 or -.76 ?

Would that make a difference?

I really don't know. :(