You are given a new situation: Two engineering students learned about petroleum products, While Dan learned more about plastics, Jim learned about fuels. and a hint : A major use for petroleum products is fuel for cars, trucks, airplanes, trains, and other vehicles. The chemical used are usually a mixture of compounds containing several carbon atoms in a chain. When the material is ignited, a massive amount of gas is created almost instantaneously. This increase in volume will move the pistons in an internal combustion engine to provide power. A jet plane works on a similar principle. Air comes into the front of the engine and mixes with the jet fuel. This mixture is ignited and the gases formed create a lot of pressure to push the plane forward. The idea can be seen even more clearly in the case of a rocket launch. The ignition of the fuel (either solid-state or liquid) creates gases produced under great pressure that pushes the rocket up. Please answer this question : Which student learned less about fuels for trains?
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Answer: Dan

You are given a new situation: John was studying the species in Siberia. He found that the Siberian tiger is an apex predator. It had a pretty stable population during the sixteenth century. He noted that information as case A. Then with the introduction of guns the number of Siberian tigers decreased in the seventeenth century. He noted that information as case B. and a hint : Apex predators can have profound effects on ecosystems, as the consequences of both controlling prey density and restricting smaller predators, and may be capable of self-regulation. They are central to the functioning of ecosystems, the regulation of disease, and the maintenance of biodiversity. When introduced to subarctic islands, for example, Arctic foxes' predation of seabirds has been shown to turn grassland into tundra. Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades. The removal of top-level predators, often through human agency, can cause or disrupt trophic cascades. For example, reduction in the population of sperm whales, apex predators with a fractional trophic level of 4.7, by hunting has caused an increase in the population of large squid, trophic level over 4 (carnivores that eat other carnivores). This effect, called mesopredator release, occurs in terrestrial and marine ecosystems; for instance, in North America, the ranges of all apex carnivores have contracted whereas those of 60% of mesopredators have grown in the past two centuries. Please answer this question : In case B, would the number of mesopredators be less or more than in case A?
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Answer: more

You are given a new situation: Martin is moving and he needs to make a ramp so he can load heavy furniture into his truck. He has a bad back, so he wants to use the least effort possible. Before he cuts the wood, he is trying to decide how long the ramp should be so he can move the heavy furniture easily. and a hint : For an inclined plane, the input distance is the length of the sloping surface, and the output distance is the maximum height of the inclined plane. This was illustrated in Figure above . Because the sloping surface is always greater than the height of the inclined plane, the ideal mechanical advantage of an inclined plane is always greater than 1. An inclined plane with a longer sloping surface relative to its height has a gentler slope. An inclined plane with a gentler slope has a greater mechanical advantage and requires less input force to move an object to a higher elevation. Please answer this question : If Martin builds a ramp with a very gentle slope will he need to exert more or less effort?
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Answer:
less