An object starts at rest. Its acceleration over 30 seconds is shown in the graph below: An acceleration versus time graph is shown with acceleration on the y axis from zero to seven meters per second per second and time on the x axis from zero to 30 second. The graph starts at the origin and goes to five meters per second in the first five seconds, then goes back to zero at time 10 seconds, then stays at zero until 20 seconds, then goes up to 6 meters per second until 30 seconds. Use the graph above to determine the change in speed of the object between 20 and 30 seconds? a 6 m/s b 30 m/s c 60 m/s d 180 m/s