Answer Wednesdays #MCAT question correctly to win a FREE month of Firecracker! You MUST include your reasoning in your answer and submit it before we post the correct answer tomorrow morning. Passage: One of the design problems involved in constructing satellites is figuring out how to power them for extended periods of time. Solar power works well in some applications, but in situations where sunlight is not constantly available, another power source is necessary. A good power source needs to be low maintenance and have a constant output. The most common solution to this problem is to use radioisotope thermoelectric generators (RTGs). RTGs are devices that convert heat from radioactive isotopes directly into electrical energy. Only about 3-7% of the heat is converted into electricity, but since there are no moving parts to wear down and the power source is fairly constant, it is a good choice for powering satellites. The Voyager 1 spacecraft was equipped with a series of RTGs to power its instruments at its launch 37 years ago. The RTGs in total produced 470W of energy. Questions 3: If the satellite started with 13.5 kg of Plutonium-238 (the radiation source) at its launch, how much is left now? The decay constant for Pu-238 is 0.0079 yr^-1. A) 18.1kg B) 10.1kg C) 0.75 kg D) 1.33 kg firecracker.me
Posted on: Wed, 18 Jun 2014 18:16:07 +0000
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