Question

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 .​

Answer 1

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.