An enormous thunderstorm covers Dallas-Ft. Worth. Your best friend Clark is a storm chaser and heads to the center of the storm to take some readings while you stay dry at home. While Clark is at the center of the storm, he sees and hears lightning strike a tree that is 160 m from where he is standing. You are 137 km from the tree. How long does it take for the sound to reach Clark? Assume the speed of sound is 343 m/s.

The sound takes 0.47 seconds to reach Clark

Explanation:

We are analyzing the speed of the sound not the lightning. We need to ignore the irrelevant parameters in the question and make use of only those necessary to answer the question.

Speed of sound = 343m/s

Distance between Clark and the tree = 160m

recall, time of travel =

time =

∴ It takes the sound≈ 0.47 seconds to reach clark

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.

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electrical energy

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ligh energy