Answer:
18 meters.
Step-by-step explanation:
There is a constant acceleration for 3 seconds, reaching 4 m/s. This, when drawn on a velocity/time graph, creates a diagonal line. The area underneath this line, which is the distance it travels, is found by the following: 0.5(l*h), the formula used to find the area of a triangle.
0.5(3*4)=6m
There is then a constant deceleration of 0.5m/s for 4 seconds. This does also create a diagonal line on a velocity/time graph, but it doesn't go down to 0. What I do is split it up so that a triangle and a rectangle are created from the shape made. The triangle has a height of 2, and a length of 4, so we use the same formula used before.
0.5(2*4)=4m
Now, all that remains is a rectangle of height 2 and a length of 4, so we find the area of it.
2*4=8m
Finally, we add each of these up.
6m+4m+8m=18m
Sorry if the step by step process was poorly explained, I'm not the best at explaining. Hope this helped, though. :^)