Question

Joseph DeLoach of the United States set an Olympic record in 1988 for the 200-meter dash with a time of 19.75 seconds. What was his average speed? Give your answer in meters per second and miles per hour.

Answer 1

Answer:

The average speed was 10.12 m/s or 22.96 mi/h

Explanation:

The average speed is defined as:

$v = \frac{d}{t}$   (1)

Where d is the total distance traveled and t is the passed time.

For the special case of Joseph DeLoach, he traveled a total distance of 200 meters in 19.75 seconds. Those values can be introduced in equation 1:

$v = \frac{200 m}{19.75 s}$

$v = 10.12 m/s$

That means that Joseph DeLoach traveled a distance of 10.12 meters per second.

To represent the result in miles per hour, it is necessary to know that 1 mile is equivalent to 1609 meters.

$200 m x \frac{1 mi}{1609 m}$ ⇒ 0.124 mi

it is needed to express the given time in units of hour. 1 hour is equivalent to 3600 seconds.

$19.75 s x \frac{1 h}{3600 s}$ ⇒ 0.0054 h

Then, equation 1 is used with the new representation of the values.

$v = \frac{0.124 mi}{0.0054 h}$

$v = 22.96 mi/h$