Question

A vehicle travels half the distance (L) with speed ` V_1` and the other half with speed ` V_2`, then its average speed is .
A. (a) ( V_1 + V_2)/2`
B. (b) ` (2 V_1 + V_2)/(V_1 +V_2)`
C. (c ) ` ( 2 V-1 V_2)/(V_1 +V_2)`
D. (d)` (L(V_1+V_2))/(V_1 V_2)`

Answer 1

Correct Answer - C
Time taken to travel first hlf distance , `t_1 = (L//2)/v_1` = L/(2 v_10`
Time taken to travel second half distance , ` t_1 = ( L//2)/v_1) = L/(2 v_2)`
Total time ` = t_1 + t_1 = L/( 2 v_1 = L/(2 v_2) = L/2 [1/v-1 + 1/v_2]`
Average speed = (total distance ) / ( total tiem ) = L/( L/2 [1/v-1 = 1/v-2] = ( 2 v_1 v-2)/(v_1 + v-2)`.