Final answer:
The formula for the slope of a secant line is (y2 - y1)/(x2 - x1), where (x1, y1) and (x2, y2) are the coordinates of two points on the curve.
Step-by-step explanation:
The formula for the slope of a secant line can be determined by finding two points on the curve and using the slope formula. The slope formula is given by: m = (y2 - y1)/(x2 - x1), where (x1, y1) and (x2, y2) are the coordinates of the two points.
In the given information, the endpoints of the tangent line are (260 m/s, 51 s) and (210 m/s, 1.0 s). Plugging these values into the slope formula, we get: m = (210 m/s - 260 m/s)/(1.0 s - 51 s) = 1.0 m/s².