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The world's record in the 100 m dash is 9.69 seconds and in the 100 yard dash is 9.21 seconds.

Afind the speed in mi/h of the runner who set the record of 9.69 seconds.
Bfind the speed in mi/h of the runner who set the record of 9.21 seconds.

Verified Answer :

Hagrid

Speed is equivalent to the distance traveled divided by the time it takes to travel that certain distance. 
To solve this problem convert the units first from meter and yards to miles. 100 metes is 0.0621371mi and 100 yards is 0.0568182 yard. 9.69s = 0.002691667 hr and 9.21s = 0.002558333

A.) 23mi/hr
B.) 22.20mi/hr

Answer:

A) The speed of the runner is 23.085 mile/hr.

B) The speed of the runner is 22.209 mile/hr.

Explanation:

\(Speed=\frac{\text{Distance covered}}{\text{Time taken}}=\frac{D}{T}\)

A) Distance covered in 9.69 seconds = 100 m

1 mile = 1609.34 m

\(100 m =100\times \frac{1}{1609.34} miles=0.062137 miles\)

1 hour = 3600 seconds

9.69 s = \(9.69\times \frac{1}{3600} hr=0.002691 hr\)

Speed of the runner = \(\frac{0.062137 mile}{0.002691 hr}=23.085 mile/hr\)

The speed of the runner is 23.085 mile/hr.

B) Distance covered in 9.21 seconds = 100 yards

1 mile = 1760 yards

\(100 yards =100\times \frac{1}{1760 } miles=0.05681 miles\)

1 hour = 3600 seconds

9.21 s = \(9.21\times \frac{1}{3600} hr=0.0025583 hr\)

Speed of the runner = \(\frac{0.05681 mile}{0.0025583 hr}=22.209 miles/hr\)

The speed of the runner is 22.209 mile/hr.

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