How to Convert a Velocity-Time Graph to a Position-Time Graph?

[pebbles3]

Homework Statement

I have to calculate the displacements from a velocity-time graph to make a position-time graph.
The velocity-time graph from the question is attached.

Homework Equations

d=vt

The Attempt at a Solution

To calculate the values for a position-time graph, I first converted all the velocities from km/h to km/min to match the time.
The truck travels at 70 km/h (1.16 km/min) for 10 mins: 1.16 x 10 = 11.6
It then travels at 80 km/h (1.33 km/min) for 30 mins: 1.33 x 30 = 40
It then travels at 75 km/h (1.125 km/min) for 5 mins: 1.25 x 5 = 6.25
It then travels at 60 km/h (1.0 km/min) for 2.5 mins: 1.0 x 2.5 = 2.5
And then travels at 55 km/h (0.9 km/min) for 22.5 mins: 0.91 x 22.5 = 20.6

I drew a position-time graph which is attached. I just want to know if I did this right because the graph I made looks a little weird to me.

 

[phinds]

Since the truck keeps traveling in the same direction, how is it that your position graph shows it reversing direction?

 

[pebbles3]

Since the truck keeps traveling in the same direction, how is it that your position graph shows it reversing direction?

Ah, I think I've got it now. Does this look right?

 

[phinds]

I didn't check the details but that's certainly the right idea.

 

[pebbles3]

Ok, thanks!