Thursday, May 27, 2010

It took me about an hour to solve this 2 questions..

2 question for about an hour.. I need to study man.. This is all about Differential Equation.. Here are the questions:


Newton’s law of cooling

                A thermometer reading is 75˚ F is taken out of where the temperature is 20˚F. The thermometer reading is 30˚F, 4 min later. Find (a) the thermometer reading 7 min after the thermometer was brought outside, and (b) the time taken for the reading to drop from 75˚F to within a half degree of the air temperature.

Law of growth and decay
                A certain radioactive substance has a half-life of 38 hrs. Find how long it takes for 90% of the radioactive substance to be decomposed.

Good luck to me... Hope I can answer the examination set on Monday, May 31, 2010. If this took me about an hour what if it is composed of 6 questions? !!!!

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