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.

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Answer 1
24 m/s


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


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


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


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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