Question 3
The velocity–time graph of an object moving at a uniform velocity of 6 m s-1 is shown below.
| t (s) | 0 | 8 |
|---|---|---|
| v (m s⁻¹) | 6 | 6 |
What is the object's displacement over the 8 seconds?
The right answer is the one marked above.
48 m. With a uniform velocity the graph is a straight line parallel to the x axis, and the region under it is a rectangle.
displacement = velocity × time = 6 m s-1 × 8 s = 48 m
That is exactly the area of the shaded rectangle: 6 × 8 = 48. The area of a rectangle is found by multiplying the distance along the x axis (the time) by the height along the y axis (the velocity).
24 m comes from halving it as though it were a triangle — but the velocity here is not building up, it is constant.