At a soccer practice, the players run sprints. They start at the goal, run 10 m toward the center of the field and then run back to the goal. Then they run 20 m toward the center of the field and back to the goal. Finally they run 30 m toward the center of the field, turn around, and run back to the goal again. One player times herself to try and beat her personal best time. She runs the first 10 m in 2.5 s and gets back to the goal in 2.8 s. Then she runs the 20-m sprint in 5.7 s and gets back to the goal in 6.7 s. She runs the final 30-m sprint in 12 s and gets back to the goal in 15 s. What was her average velocity for the entire exercise?

Question

Eliezer Chapman

Physics

19 April, 21:31

At a soccer practice, the players run sprints. They start at the goal, run 10 m toward the center of the field and then run back to the goal. Then they run 20 m toward the center of the field and back to the goal. Finally they run 30 m toward the center of the field, turn around, and run back to the goal again. One player times herself to try and beat her personal best time. She runs the first 10 m in 2.5 s and gets back to the goal in 2.8 s. Then she runs the 20-m sprint in 5.7 s and gets back to the goal in 6.7 s. She runs the final 30-m sprint in 12 s and gets back to the goal in 15 s. What was her average velocity for the entire exercise?

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Answers (1)

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Nicole Blankenship · Answer 1

2.68 m/s

Explanation:

The total distances she runs in this exercise is:

First 10m sprint and back = 10 * 2 = 20m

2nd 20m sprint and back = 20 * 2 = 40m

The last 30m sprint and back = 30 * 2 = 60m

So the total distance = 20 + 40 + 60 = 120m

The total time she takes to run all these tracks:

2.5 + 2.8 + 5.7 + 6.7 + 12 + 15 = 44.7s

So here average speed for the entire exercise is

120 / 44.7 = 2.68 m/s