Answer:
![a = 4 m/s/s](https://img.qammunity.org/2019/formulas/physics/middle-school/i73gkh42q7pny53u5pfp1ik1qaaflfjdbc.png)
Step-by-step explanation:
As we know that the acceleration of an object is defined as the rate of change in velocity of the object
so we can say it is given as
![a = (dv)/(dt)](https://img.qammunity.org/2019/formulas/physics/middle-school/emwr3wviwx3v6hwaf6nm6bd1rcdrvwxsxi.png)
so if we have a graph of velocity and time then rate of change in velocity is given by the slope of v-t graph
so here for segment A slope of the graph is
![a = (v_2 - v_1)/(\Delta t)](https://img.qammunity.org/2019/formulas/physics/middle-school/j0umo1c6zi9yuur9cc7nitsbtpnuoagvb0.png)
![a = (20 - 0)/(5 - 0)](https://img.qammunity.org/2019/formulas/physics/middle-school/nn2hh6za9wa7xn0f7fp58rskou3vd8erxy.png)
![a = 4 m/s/s](https://img.qammunity.org/2019/formulas/physics/middle-school/i73gkh42q7pny53u5pfp1ik1qaaflfjdbc.png)