velocity and acceleration graph question

[elihid98]

I am reviewing for a test. I can't work out how B is the correct answer. I look at the possible answers now and I would most probably choose A.

It gives us a velocity-time graph and we're supposed to find the corresponding acceleration-time graph. I don't quite see how B works in the sense that acceleration seems to be constant, yet how does that make sense if the function is not linear, doesn't the acceleration vary? 

 

It's in Spanish, but I don't think that should matter too much. 

Thanks in advance  

wait what. I'm sorry, I'm new to this. The picture is there twice whoops. 

[Vioh]

I am reviewing for a test. I can't work out how B is the correct answer. I look at the possible answers now and I would most probably choose A.

It gives us a velocity-time graph and we're supposed to find the corresponding acceleration-time graph. I don't quite see how B works in the sense that acceleration seems to be constant, yet how does that make sense if the function is not linear, doesn't the acceleration vary? 

 

It's in Spanish, but I don't think that should matter too much. 

Thanks in advance

wait what. I'm sorry, I'm new to this. The picture is there twice whoops. 

 

The only possibility that I can think of is that there must be something wrong with your answer keys. The correct answer for this question is A without a doubt

[elihid98]

 

I am reviewing for a test. I can't work out how B is the correct answer. I look at the possible answers now and I would most probably choose A.

It gives us a velocity-time graph and we're supposed to find the corresponding acceleration-time graph. I don't quite see how B works in the sense that acceleration seems to be constant, yet how does that make sense if the function is not linear, doesn't the acceleration vary? 

 

It's in Spanish, but I don't think that should matter too much. 

Thanks in advance

wait what. I'm sorry, I'm new to this. The picture is there twice whoops. 

 

The only possibility that I can think of is that there must be something wrong with your answer keys. The correct answer for this question is A without a doubt

 

Alright yeah, I thought so too, but I still wanted to doublecheck. Thank youu

[MitchCampbell]

You're both right, the answer absolutely must be A. To start with a velocity/time graph and get to the acceleration/time graph, you just take the derivative (gradient) at each point.

 

Just looking at the start point on the v(t) graph, it's got a negative slope. So for sure, the corresponding initial point on the a(t) graph should be a negative value.

The graph continues to have a negative slope as you go to the right, but it gets shallower as you approach the 'bottom' of the graph (halfway through). That zero slope is represented by the a(t) graph having a value of zero. 

 

Then the v(t) graph continues to increase, and that's shown in the a(t) graph as larger positive values.

 

To see how to work with any displacement/time, velocity/time, or acceleration/time graphs:

https://www.youtube.com/watch?v=3qFkT2KbcqM&list=PL6145CFE556385A9A&index=3

 

Your teacher / markscheme has an error. Well done!