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AnnZ [28]
3 years ago
11

A 64.9 kg sprinter starts a race with an acceleration of 3.89 m/s2. She keeps this acceleration for 17 m and then maintains the

velocity for the remainder of the 100-m dash, what will be her time for the race?
Physics
1 answer:
xxMikexx [17]3 years ago
3 0

Answer:

Time of race  = 10.18 s

Explanation:

She keeps this acceleration for 17 m and then maintains the velocity for the remainder of the 100-m dash

Time to travel 17 m can be calculated

         s = ut + 0.5at²

         17 = 0 x t + 0.5 x 3.89 x t²

          t = 2.96 s

Velocity after 2.96 seconds

          v = 3.89 x 2.96 = 11.50 m/s

Remaining distance = 100 - 17 = 83 m

Time required to cover 83 m with a speed of 11.50 m/s

          t=\frac{83}{11.50}=7.22s

Time of race = 2.96 + 7.22 = 10.18 s

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Answer:

Explanation:

In the decibel scale , intensity of sound changes logarithmically as follows

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\frac{I}{10^{-12}} = 10^{7.1}

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Putting the given values for 71 dB

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A = 7.74 x 10⁻⁸ m

For 54 dB sound

10^{-6.6} = 2π² x 504²xA²x 1.21 x  346

A² = 1.1978 x 10⁻¹⁶

A = 1.1 x 10⁻⁸ m

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