A car moves with an average speed of x m/s during the first half and 2 x m/s in the second half . Find the average speed of the entire journey .
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A car moves with an average speed of x m/s during the first half and 2 x m/s in the second half . Find the average speed of the entire journey .
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Answer:
(4x / 3) m/s
Explanation:
Taking the distance and time to be d and t respectively,
Average speed for the first half = x m/s
Distance covered in the first half = d/2 m
Time taken = Distance / Speed
⇒ (d/2) / x
= d/2x seconds
Average speed for the second half = 2x m/s
Distance covered in the second half = d/2 m
Time taken = Distance / Speed
⇒ (d/2) / 2x
= d/4x seconds
Total time taken (t) = (d/2x) + (d/4x)
⇒ (2d + d) / 4x
= (3d / 4x) seconds
Average speed = Total distance / Total Time
⇒ d/t
⇒ d / (3d/4x)
= (4x / 3) m/s
Hence, the average speed of the car in the full journey is (4x / 3) m/s.