Concept explainers
Cooling an Engine Suppose you’re driving your car on a cold winter day (
(a) Solve the equation for T.
(b) Use part (a) to find the temperature of the engine after
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Algebra and Trigonometry (MindTap Course List)
- Forensics At 8:30 A.M., a coroner went to the home of a person who had died during the night. In order to estimate the time of death, the coroner took the person’s temperature twice. At 9:00 A.M. the temperature was 85.7F, and at 11:00 A.M. the temperature was 82.8F. From these two temperatures, the coroner was able to determine that the time elapsed since death and the body temperature were related by the formula t=10lnT7098.670 where t is the time in hours elapsed since the person died and T is the temperature (in degrees Fahrenheit) of the person’s body. (This formula comes from a general cooling principle called Newton’s Law of Cooling. It uses the assumptions that the person had a normal body temperature of 98.6F at death and that the room temperature was a constant 70F.) Use the formula to estimate the time of death of the person.arrow_forwardDrug Concentration When a drug is administered orally, it takes some time before the blood concentration reaches its maximum level. After that time, concentration levels decrease. When 500 milligrams of procainamide is administered orally, one model for a particular patient gives blood concentration C, in milligrams per liter, after t hours as C=2.65(e0.2te2t) What is the maximum blood-level concentration, and when does that level occur?arrow_forwardCharging a Battery The rate at which a battery change is slower the closer the battery is to its maximum change c The time (in hours ) required to change a fully discharged battery to a charge C is given by t=In(1cc) Where k is a positive constant that depends on the battery. For a certain battery, k=0.25 . If this battery is fully discharged, how long will it take to change to 90% of its maximum charge c ?arrow_forward
- Solving an Equation of Change Solve the equation of change dfdx=3 if the initial value of f is 7.arrow_forwardRadioactive Decay The half-life of a radioactive substance is the time H that it takes for half of the substance to change form through radioactive decay. This number does not depend on the amount with which you start. For example, carbon-14 is known to have a half-life of H=5770 years. Thus, if you begin with 1 gram of carbon-14, then 5770 years later you will have 12 gram of carbon-14. And if you begin with 30 grams of carbon-14, then after 5770 years there will be 15 grams left. In general, radioactive substances decay according to the formula A=A00.5tH Where H is the half-life, t is the elapsed time, A0 is the amount you start with the amount when t=0, and A is the amount left at time t. a. Uranium-228 has a half-life H of 9.3 minutes. Thus, the decay function for this isotope of uranium is A=A00.5t9.3, where t is measured in minutes. Suppose we start with grams of uranium-228. i. How much uranium-228 is left after 2 minutes? ii.How long will you have to wait until there are only 3 grams left? b. Uranium-235 is the isotope of uranium that can be used to make nuclear bombs. It has a half-life of 713 million years. Suppose we start with 5 grams of uranium-235. i. How much uranium-235 is left after 200 million years? ii. How long will you have to wait until there are only 3 grams left?arrow_forwardFalling-Body Problems Suppose an object t dropped from a height h0 above the ground. Then its height after t seconds is given by h=16t2+h0 , where h ¡s measured in feet. Use this information Lo solve the problem. If a ball is dropped from 288 ft above the ground, how bug does it take to reach ground level?arrow_forward
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