If the average speed of an object moving in a variable speed straight line is 6m / s in the first half of the distance and 10m / s in the second half of the distance, the average speed in the whole distance is () A. 7.04m/sB. 7.50m/sC. 8m/sD. 8.24m/s

If the average speed of an object moving in a variable speed straight line is 6m / s in the first half of the distance and 10m / s in the second half of the distance, the average speed in the whole distance is () A. 7.04m/sB. 7.50m/sC. 8m/sD. 8.24m/s

Let s be the total distance, T1 = 12s6 for the first half of the distance, T2 = 12s10 for the second half, v = st1 + T2 = 7.50 M / s for the average speed in the whole distance, so B is correct

For an object moving in a straight line with variable speed, if the average speed in the first half of the journey is 6m / s, the average speed in the second half of the journey is 10m / s,
Then the average speed in the whole course is 2v1v2 / (V1 + V2) = 120 / 16 = 7.5m/s

2v1v2 / (V1 + V2) = vpin (1) is derived from the formula. Let me give you the basic formula of velocity s = VT, then S1 = v1t1, S2 = v2t2, S1 = S2, then vpin = stotal / ttotal = (S1 + S2) / (T1 + T2) = (S1 + S2) / [(S1 / V1) + (S2 / V2)], because S1 = S2, if you remove the denominator, then you have to

If the average speed of an object moving in a variable speed straight line is 6m / s in the first half of the distance and 10m / s in the second half of the distance, the average speed in the whole distance is ()
A. 7.04m/sB. 7.50m/sC. 8m/sD. 8.24m/s

Let s be the total distance, T1 = 12s6 for the first half of the distance, T2 = 12s10 for the second half, v = st1 + T2 = 7.50 M / s for the average speed in the whole distance, so B is correct