Question

3. Abdul, while driving to school, ccomputes the average speed for his trip to be 20km h-1. On his return trip along the same route , there is less traffic and the average speed is 30km h-1. What is averagr speed of abdul's trip??​

Answer 1

$let \: the \: distance \: between \: school \: and \: home \: is \: \: \: \: \: s$

$while \: going$

${t}^{2} = \frac{s}{ {v}^{2} }$

$and \: while \: returning$

${t}^{2} = \frac{8}{ {v}^{2} }$

$total \: distance \: = 2s \: and \: total \: time \: is$

$t = {t}^{1} + {t}^{2}$

$vav = \: \frac{2s}{t} = \: \frac{2s}{ \frac{s}{ {v}^{1} } \: \: \: \: \frac{s}{ {v}^{2} } }$