In 1926, Gertrude Ederle was the first American woman to swim across the English Channel. At that time, she set the world record for crossing the channel with an average speed of 0.725 m/s. Assuming that the distance Ederle swam was 37.9 km SE (the shortest distance between England and France), how long did it take her to swim the channel?

To find out how long it took Gertrude Ederle to swim across the English Channel, we'll need to follow these steps:

1. Convert the distance from kilometers to meters:
Gertrude swam 37.9 km. Since 1 kilometer is equal to 1000 meters, we convert it to meters.

[tex]\[
37.9 \, \text{km} = 37.9 \times 1000 \, \text{m} = 37900 \, \text{m}
\][/tex]

2. Calculate the time in seconds:
We know her average speed was 0.725 meters per second. To find out the time it took, we use the formula:

[tex]\[
\text{Time} = \frac{\text{Distance}}{\text{Speed}}
\][/tex]

Therefore,

[tex]\[
\text{Time} = \frac{37900 \, \text{m}}{0.725 \, \text{m/s}} = 52275.86 \, \text{seconds}
\][/tex]

3. Convert the time from seconds to hours, minutes, and seconds:
- First, convert the total seconds to hours:

[tex]\[
\text{Hours} = \frac{52275.86}{3600} \approx 14.52 \, \text{hours}
\][/tex]

- To find the remaining minutes, take the fractional part of the hours and convert it to minutes:

[tex]\[
\text{Minutes} = (14.52 \, \text{hours} - 14 \, \text{hours}) \times 60 \approx 31.26 \, \text{minutes}
\][/tex]

- Finally, convert the fractional part of the minutes to seconds:

[tex]\[
\text{Seconds} = (31.26 \, \text{minutes} - 31 \, \text{minutes}) \times 60 \approx 15.86 \, \text{seconds}
\][/tex]

Combining these results, Gertrude Ederle took approximately:

- 14 hours
- 31 minutes
- 15.86 seconds

to swim across the English Channel.