9514 1404 393
Answer:
E. 0 meters
Explanation:
The net displacement is the area under the velocity curve, taking signs into account.
Here, the shape of the curve is triangular, so we can use geometry to figure the area. The area of a triangle is given by ...
A = 1/2bh
For the first 40 seconds, the triangle has a base of (40 s) and a height of (+4 m/s). Then the area is ...
A = (1/2)(40 s)(4 m/s) = 80 m
For the next 40 seconds, the triangle has a base of (40 s) and a height of (-4 m/s). The area of that triangle is ...
A = (1/2)(40 s)(-4 m/s) = -80 m
Then the net displacement is 80 m - 80 m = 0 m over the 80 s period.
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Additional comment
You can see right away that the curve is symmetrical about the point (40, 0), so will have a net zero area on the interval [0, 80].
