Is there more to consider when determining if velocity is constant from data?

[Robershky]

I am doing make-up questions from my General Physics test. This is pretty easy stuff, and I thought I answered correctly, but according to my teacher's comments on my paper it seems like I'm missing something.

Homework Statement

For the data provided, is the velocity for this object constant? How do you know?

Displacement (cm): 15, 100, 190, 290, 380
Time (seconds): 0, 3, 6, 9, 12

Homework Equations

The Attempt at a Solution

Just by looking at the data I would say it's not constant, but after graphing it, the trend curve is linear, so I wrote my answer as

Yes, because the trend curve is linear

The teacher seemed to accept the answer as correct, but wanted more information because after my answer she wrote

and...?

Is there any other way to explain the fact that the data is linear?

 

[Sheneron]

I sure would be curious to find out what exactly your teacher wants.

 

[peleus]

Yes, because the trend curve is linear and... you're a great teacher?

 

[PhanthomJay]

Hint: If the line had a significant slope, the v-t graph would still be linear, but the velocity would not be constant (the object would be accelerating).

 

[Robershky]

Hint: If the line had a significant slope, the v-t graph would still be linear, but the velocity would not be constant (the object would be accelerating).

But the graph is for position vs time, which is linear. Therefor the Velocity vs. Time graph would have a slope of 0, making it constant velocity.

 

[PhanthomJay]

But the graph is for position vs time, which is linear. Therefor the Velocity vs. Time graph would have a slope of 0, making it constant velocity.

You're right, i messed that up big time. So I guess you could say "linear with a slope of v'?

 

[Robershky]

PhanthomJay: Yeah, I guess the only information I could add is the trend line equation or the slope value. I guess I'll add that and hope it's good enough, thanks.