Answer: The velocity of the vechicle at 0 s is 0 m/s
Step-by-step explanation:
The Velocity vs. Time graph of this situation is shown in the attached image. As we can see, we have five segments:
1) When the vehicle accelerates from 0 to 30 m/s in 10 seconds, which means at 0 seconds the vehicle's velocity was 0 m/s. In addition, as the vehicle goes from zero to a positive velocity, we have a positive slope.
2) Then the vehicle travels for 15 seconds at a constant velocity, that is why we do not have a slope in this section, since the vehicle kept its 30 m/s.
3) The vehicle comes to a stop in the next 5 seconds, that is why we observe an abrupt change in the graph and a negative slope.
4) The car waits 10 seconds in that stop, again we have a line with no slope
5) Finally, the car accelerates from 0 to -10 m/s in the next 5 seconds. This means the car changed its direction.