On today's streets, most vehicles are equipped with hydrocarbon-poweredengines. When fuel such as gasoline reacts (burns) with oxygen in air, this combustion process produces carbon dioxide and water along with heat. This heat causes the products (CO2 and H2O) to expand, which pushes the pistons outward. The vehicle's cooling system then removes the excess heat (heat lost to the surroundings). If the expanding gases do 510 J of work on the pistons and the system loses 455 J to the surroundings as heat, calculate the change in energy (∆E) in J and kJ.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them  

the objects have the same charge.