Final answer:
The statement is true; the slope of the velocity-time curve at a specific time indicates the velocity of the jet car, which in this scenario would be 115 m/s at t = 20 s if verified.
Step-by-step explanation:
The statement is True. To determine the velocity of a jet car at a specific point in time on a graph, one can take the slope of the velocity-time curve at that point. If the graph shows a straight line, then the slope of that line at any point will be the same, and it represents the velocity of the jet car. However, if the curve is not a straight line, the slope of the curve at t = 20 s must be calculated using tangent lines or derivative concepts to find the instantaneous velocity at that moment. For this case, if you've verified that the slope of the curve at t = 20 s is 115 m/s, then the velocity of the jet car at that time is indeed 115 m/s.