AS Daily A Level Physics question
Along a straight track, a trolley travels 8 m forward in 4 s, remains stationary for 2 s, then travels 4 m backward in 2 s. Using the total elapsed time, which statement must be true about its average speed and the magnitude of its average velocity?
Answer
The correct answer is A.
Correct: A — The average speed is three times the magnitude of the average velocity. A Total distance is 12 m and displacement is 4 m over the same total time of 8 s, so (12/8) ÷ (4/8) = 3. B Wrong because reversing direction makes distance larger than displacement even in one dimension, so they are not equal. C Wrong because 50% greater would imply a ratio of 1.5, but the correct ratio is 3. D Wrong because total distance cannot be less than the magnitude of displacement; the stop increases the time for both measures equally and doesn’t reverse that inequality.