Finding displacement from position time graph

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Displacement is calculated as the change in position over a time interval, defined as the final position minus the initial position. In this case, the final position is -15 meters and the initial position is +25 meters, resulting in a displacement of -40 meters. There is no assumption about direction needed for this calculation; it is strictly based on the positions provided. The answer key may contain an error if it suggests a different value. The correct displacement is confirmed to be -40 meters, including the necessary units.
syllll_213
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Homework Statement
For e I am asked to find the displacement of the object, and I could find the total distance travelled (25m + 15m )= 40m and I assumed the direction is the same therefore it will be the displacement for the object. However the answer is -35m and I am unsure why.
Relevant Equations
distance travelled = area under velocity time graph
Screenshot 2025-06-02 at 8.52.33 am.webp
 
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Its displacement is its change in position between over the time interval. Final position ( relative to coordinate frame) minus its initial position relative to coordinate frame. What do you get for that?
 
-40?
 
syllll_213 said:
-40?
Yeah, that’s what I get too (meters-don’t forget units). So I suspect an error with the answer key.
 
Last edited:
syllll_213 said:
. . . I assumed the direction is the same . . .
No such assumption is warranted. Displacement is (final position) - (initial position).

Here, the final position is -15 m and the initial position is +25 m.
So the displacement is (-15 m)-(+25 m) = -40 m.
 
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