Question 936269: A sprinter runs the 100-meter dash, with the wind behind him, in 9.96 seconds. He then runs the same distance in the other direction and 11.79 seconds. About how fast is the wind blowing? About how fast does the sprinter run when there is no wind?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A sprinter runs the 100-meter dash, with the wind behind him, in 9.96 seconds. He then runs the same distance in the other direction and 11.79 seconds. About how fast is the wind blowing? About how fast does the sprinter run when there is no wind?
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With-wind DATA:
time = 9.96 sec ; distance = 100 meters ; rate = d/t = 100/9.96 m/sec
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against-wind DATA:
time = 11.79 sec ; distance = 100 meters ; rate = d/t = 100/11.79 m/sec
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Equations:
r + w = 100/9.96
r - w = 100/11.79
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Add the and solve for "r":
2r = 10.04 + 8.48
r = 18.52/2 = 9.26 meters/sec (runner's speed when there is no wind)
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Subtract the two equations to get:
2w = 10.04-8.48
w = 0.78 meters/sec (speed of the wind)
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Cheers,
Stan H.
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