Position vs time graph that relates to a constant non-zero acceleration?

[gibson101]

I know that a constant acceleration would mean that the position is changing, and the position would be moving, and the speed would be changing, (increasing). I would eliminate the far right two choices because the position is changing on them and they are moving at a constant speed, and a constant speed means that there isn't any acceleration, and for the same reason I would eliminate the far bottom left choice. Oh. and I'm not sure what it means by non-zero acceleration?

 

[Mike Pemulis]

I would eliminate the far right two choices because the position is changing on them and they are moving at a constant speed, and a constant speed means that there isn't any acceleration, and for the same reason I would eliminate the far bottom left choice.

That's right. Now we have to choose among the other five.

Oh. and I'm not sure what it means by non-zero acceleration?

The acceleration is not zero... that's it.

Now, all of the five remaining graphs are curved, so we know the slopes are changing, so they all have nonzero acceleration. However, not all of them have CONSTANT acceleration. We need to eliminate the graphs that have changing acceleration.

Here is one way to look at it. The acceleration is the rate of change of the velocity, which is the rate of change of the position. Your graphs are position versus time -- so velocity is given by the slope of the graph, and the acceleration is given by the change in the slope. If acceleration is constant, that means the change in the slope (not the slope itself) is always the same -- in other words, it is either always increasing or always decreasing. Which of the graphs satisfy this requirement?

 

[gibson101]

Oh, so if it were zero then the object would still be moving , but it would just moving at a constant speed, and therefore have zero acceleration. And this would just be indicated with a horizontal line on the graph right?

 

[gibson101]

the top far left and the top 3rd over?

 

[gibson101]

horizontal line on an acceleration graph i mean

 

[gibson101]

Need help with these two questions. I have what i thought was correct.

 

[gibson101]

anyone?

 

[gibson101]

Wait, for the first graph, would the acceleration be constant? I actually think that was my mistake and that should be false, cause if it were constant then the line would be horizontal correct? NEVERMIND! I'm thinking of an acceleration graph, it's asking about the velocity vs time graph. The acceleration is constant because the line on the velocity graph (picture 1) is straight.

 

[gibson101]

still need help on the three graphs above.