Question

what is the velocity of the object at time t = 4 seconds?
position (m)
time (s)
5 m/s
40 m/s
20 m/s
10 m/s
250 m/s
50 m/s
125 m/s

Explanation:

Step1: Recall velocity formula

Velocity $v=\frac{\Delta x}{\Delta t}$, where $\Delta x$ is change in position and $\Delta t$ is change in time. For a position - time graph, velocity is the slope of the line.

Step2: Select two points on the line

Let's take the points $(0,0)$ and $(4,40)$. Here, $x_1 = 0$, $x_2=40$, $t_1 = 0$, $t_2 = 4$.

Step3: Calculate the slope

$v=\frac{x_2 - x_1}{t_2 - t_1}=\frac{40 - 0}{4 - 0}=\frac{40}{4}=10$ m/s.

Answer:

10 m/s