Lab Manual 2005

Constant Net Force ModelSituation: At the heart of dynamics is the notion of net force. The constant net force modelsays that when the net force on an object is non zero (F net ≠ 0), then the objectundergoes constant acceleration.EX 1: Consider two identical cars stopped on a level road at a stoplight. The driver of car A isvery aggressive and will press the gas peddle to the floor when the light turns green. CarB’s driver is more cautious and will only press the gas peddle a quarter of the way down.Both drivers press on the gas as soon as the light changes.What type of motion will each car have after the light changes colour?What dynamic model applies to each car?How might the motion of each car differ? Explain how and guess why this is so.What variables might be displayed here? Which could be independent and which should bedependent? What factor seems to be held constant?EX 2: Now consider this. Two identical tractor trailers are stopped at the same intersection asabove. Both drivers are equally aggressive and will press on the gas all the way when thelight turns green. However, one truck is fully loaded with 2 tonnes of steel pipes and theother is completely empty.What type of motion will each truck have after the light changes colour?What dynamic model applies to each truck?How might the motion of each truck differ? Explain how and guess why this is so.What variables might be displayed here? Which could be independent and which should bedependent? What factor seems to be held constant?- 27 -