Question

甲从a点以5m/s到b点 然后以3m/s从b回到a点 求他的总平均速度 75m/s

Answer 1

s/5=t1,s/3=t2,；

v=2s/(t1+t2)

=2s/(s/5+s/3)

=30/8

=3.75m/s.