Physics Review Question Unit: Mechanics Year: 1990 Question#: 4 Question: A car moving at a speed of 8.0 meters per second enters a highway and accelerates at 3.0 meters per second 2. How fast will the car be moving after it has accelerated for 56 meters? (1 ) 24m/s (2 ) 20m/s (3 ) 18m/s (4 ) 4.0m/s What is this question really asking? Explanation by: Liz M. [ Return to question menu ] Answer 1 24 m/s INCORRECT To answe this question you need to plug the given numbers into the formula and solve for vf. It looks as though you just multiplied the 8 and the 3. That does not answer the question. return to top Answer 2 20 m/s CORRECT You plugged the numbers into the formula: after doing the calculations, you came up with the answer 20m/s as the final velocity. Good answer. return to top Answer 3 18 m/s INCORRECT I am unsure how you got this answer. Perhaps you divided the 56 by the 3 and came up with approximately 18. To answer this question, you need to plug the given nmbers into formula: and solve for vf. return to top Answer 4 Incorrect INCORRECT I am unsure of how you got this answer. Perhaps you divided the displacement (56m) by the 8m/s getting 7 sec, and then subtracted the 3m/s <sup>2</sup> thus getting 4m/s. To get the correct answer you must plug the given numbers into the formula: and solve for V f return to top What's this question really asking? The question is asking if the student understands how to plug in the right numbers into the right formula. It is a case of thinking it through and figuring out which variable you need to solve for. return to top |
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