Exploring Average Speed

Question

A rower wanted to determine the speed of a river's current prior to going down a particular section of the river.

She released a tracker into the river. The tracker sent her back the following information:

1. 3 seconds after the tracker was released into the river, the tracker had traveled 7.5 meters.
2. 10.1 seconds after the tracker was released into the river, the tracker had traveled 17.5 meters.

Assuming the river was flowing at a constant speed, what was the speed of the current on this section of the river?

Answer 1

Since the flow was considered to be constant the function is linear.

Start with two-pont form from Algebra

(y - 7.5) / (x - 3) = (17.5 - 7.5) / (10.1 - 3)

Can you convert ot slope-intercept form and answer?

Answer 2

for 3 seconds it went 7.5 meters or 2.5 meters per second

for 10 seconds it went 17.5 meters or 1.75 meters per second

for the last 7 seconds it went 10 meters or 1.43 meters per second

if there was no current in the last 7 meters

then the river speed is 1.43 m/sec

and the current speed is 2.5-1.43 = 1.07 m/sec for the 1st 7.5 meter stretch