Question

A vehicle travels half the distance L with speed and other half with speed , then its average speed is

• A.
• B. $\frac { 2 v _ { 1 } + v _ { 2 } } { v _ { 1 } + v _ { 2 } }$
• C. $\frac { 2 v _ { 1 } v _ { 2 } } { v _ { 1 } + v _ { 2 } }$
• D.

Answer 1

Answer: (C)

$\frac { 2 v _ { 1 } v _ { 2 } } { v _ { 1 } + v _ { 2 } }$

Answer 2

Time taken to travel first half distance,

Time taken to travel second half distance,

Total time taken

Average speed

,

$= \frac { \mathrm { L } } { \frac { \mathrm { L } } { 2 \mathrm { v } _ { 1 } } + \frac { \mathrm { L } } { 2 \mathrm { v } _ { 2 } } } = \frac { 1 } { \frac { 1 } { 2 } \left[ \frac { 1 } { \mathrm { v } _ { 1 } } + \frac { 1 } { \mathrm { v } _ { 2 } } \right] }$=