question_answer

A person travels along a straight road for the first half length with constant speed \[{{v}_{1}}\]and the second half length with a constant speed\[{{v}_{2}}\]. Average speed v is

(a) \[\frac{{{v}_{1}}{{v}_{2}}}{2({{v}_{1}}+{{v}_{2}})}\]

(b) \[\frac{2({{v}_{1}}+{{v}_{2}})}{{{v}_{1}}{{v}_{2}}}\]

(c) \[\frac{2({{v}_{1}}+{{v}_{2}})}{{{v}_{1}}+{{v}_{2}}}\]

(d) \[\frac{{{v}_{1}}+{{v}_{2}}}{{{v}_{1}}{{v}_{2}}}\]

Answer:

\[V=\frac{2{{V}_{1}}{{V}_{2}}}{{{V}_{1}}+{{V}_{2}}}\]