Q.

An object moves with speeds v1, v2 and v3 along the line segments AB, BC and CD respectively as shown in the figure. Where AB = BC and AD = 3AB, then the average speed of the object will be:                   [2023]

1 (v1+v2+v3)3  
2 v1v2v33(v1v2+v2v3+v3v1)  
3 3v1v2v3v1v2+v2v3+v3v1  
4 (v1+v2+v3)3v1v2v3  

Ans.

(3)

AB=x and BC=x

2x+CD=3x

 CD=x

<v>=3xxv1+xv2+xv3=3v1v2v3v2v3+v1v3+v1v2