(10) As shown in the figure, a marathon runner starts from point A and moves along the arrow direction of the curve ABCDE trajectory, AB, ABC, ABCD and ABCDE.

(1) can be regarded as a particle; (2)3. 125m/S2； (3) ; Direction: north by east;

Test analysis: (1) The athlete's body shape and size have little influence on the distance of marathon, so it can be regarded as a particle. ( 1)

(2) According to the formula of uniform linear motion and uniform linear motion, there are: (1)

Substitute the data to get: (1 min)

So the acceleration is:? (2 points)

(3) According to the image, the displacement of AD segment: (1)

So the average speed of players in ABCD segment is:? (2 points)

Along the east-west direction, as shown in the figure:? (2 points)