# physics

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Conventional engines ignite their fuel by using the spark from the spark plug. But in a diesel engine, the air enthers the chamber at the temperature of the atmosphere and is compressed by the piston until it reaches 550 degrees Celsius, at which time the fuel is injected itno the chamber and ignited by the hot air. There is no spark plug and no heat is put into the air. (One of the drawbacks of diesel engines is that they are hard to start in cold weather) Suppose a certain chamber has a maximum volume of .5 L and uses .05 mole of air. we can model the air as all ideal N2 and use the appropriate values from Table 15.4 (a) If the air temperature is 20 degrees Celsius what is the colume of the air (which started at .5 L) when it has been compressed enough so that its temperature has risen to 550 degrees celsius? (b) What is the change in internal energy of the air during this compression? (c) How much work did the piston do on this gas while compressing it? (d) Suppose it is cold winter morning, with air temperature 10 degrees Farenheit. If the piston compressed the air by the same amount as before, what will be the highest temperature the gas will reach in this case? (e) DO you now see why a diesel engine is hard to start in cold weather? Can you suggest any reasonable technological solutions to help start a diesel engine on a cold day?