Asked by tim
danny drove halfway from town p to town q at average speed of 60 km/h. he wants to average 80 km/h for the entire journey. What will his average speed be for the second part of his journey?
Answers
Answered by
bobpursley
speed=distance/time
60=d/2time1
but d=60*time1+V*time2
and
80=d/(time1+time2)
or
time1+time2=d/80 then
d/120+time2=d/80
time2=d/80-d/120=d/120 (3/2-1)
time2=d/240
so velocity2ndpart=(d/2)/time2
= d/2(d/240)=120km/hr
check:
time1=d/(2*60)=d/120
time2=d/(2*120)=d/240
80=d/(time1+time2)=d/(3d/240)=80
60=d/2time1
but d=60*time1+V*time2
and
80=d/(time1+time2)
or
time1+time2=d/80 then
d/120+time2=d/80
time2=d/80-d/120=d/120 (3/2-1)
time2=d/240
so velocity2ndpart=(d/2)/time2
= d/2(d/240)=120km/hr
check:
time1=d/(2*60)=d/120
time2=d/(2*120)=d/240
80=d/(time1+time2)=d/(3d/240)=80
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.