Physics Review Question Unit: mechanics Year: 1994 Question#: 9 Question: A car is traveling at a constant speed of 14 m/s along a straight highway. A tree and a speed limit sign are behind a highway. As it passes a tree, the car starts to accelerate. the car is accelerated uniformly at 2.0 m/s2 until it reaches the speed limit sign, 5.0 sec. later. 9. When the car reaches the sign, the car's speed is (1 ) less than the speed limit (2 ) greater than the speed limit (3 ) egual to the speed limit What is this question really asking? Explanation by: Danny A [ Return to question menu ] Answer 1 less than the speed limit CORRECT If the car was going 14m/s and it started to speed up at 2m/s2 for 5 seconds that means the total speed increased 10m/s (using the formula ) which you add to 14m/s which equals 24m/s. return to top Answer 2 greater than the speed limit INCORRECT If it was going for 6 seconds this would be correct. Try using to find the change in velocity then add it to the inital velocity. return to top Answer 3 equal to the speed limit INCORRECT if it was going for 5.5 seconds than this answer would be correct. Try using to find the change in velocity then add it to the inital velocity. return to top What's this question really asking? What is the car's speed after accelerating at 2m/s for 5s, if it started out going 14m/s by the time it reaches the sign? return to top This web site is designed and maintained by Science Joy Wagon and may not be reproduced or redistributed without written permission from Science Joy Wagon. Contact with comments.