Expert: Richard J. Raridon - 11/24/2010

Question
Simultaneous Equations and the Physical World?
Problem


(1) Construct a physical explanation for why the sound of thunder from a lightning strike appears after the actual bolt of lightning is observed.

(2) Devise and execute a strategy that would allow you to determine the distance to a lightning strike, given a five second time difference between seeing the lightning and hearing the thunder.

I. Under standing the problem
(a) What are the key pieces of information in the two parts of the problem statement? If desired, rewrite them in your own words.

(b) in your opinion, would it be better to approach these two problems separately, or as one large problem? explain your reasoning.

(c) DO you have all of the information you need to solve the two parts of the problem? If not, what additional information of clarification do you need? After recording the additional information that you think is necessary, research any missing information and then proceed.

(Hint) Distance= Rate x Time

II. Devise a plan

(d) For the first part of the problem state your explanation for the difference in time between when lightning is observed and the thunder is heard. how does it compare to that of others near you in the class?

(e) For the second part, describe your problem solving strategy for finding the distance from your position to the lightning strike.

(Hint)
The following facts may be helpful in solving the second part of the problem.

* The velocity of light is approximately 3.0 x 10^8 meters per second.

* The velocity of sound depends upon the temperature of the air through which the sound waves moves. With the temperature expressed in Celsius, the velocity of sound (in meters per second) can be found using the formula. v=331+0.6T

(f) Do the facts in the hint, about the speed of light and the formula for calculating the speed of sound, suggest that you should modify your initial problem solving strategy? if so, how?


III. Carry out the plan

(g) Implement your strategy, and find the distance from your position to the lightning strike.

IV. Look Back
(h) How effective was your method? do you believe that your approach is the best strategy to solve the problem?

Answer
Obviously, when the speed of light is 186,000miles/s and the speed of sound is about 1100ft/s you're always going to see the lightning before you hear the thunder.  If the time difference is 5s, then the strike was about a mile away (5280/1100).  You hardly need to bother making the temperature correction for the speed of sound.