Question

a car travels the first third distance with a speed of 10knph the second third at 20kmph and last third at 60kmph what is it's mean speed over the entire distance?​

Answer 1

Answer:

one third d at 10kmph, 20 kmph, 60 kmph

let t1, t2, t3 are times of traveled distances

let total distance is d

d/3 at 10kmph t1 = d/3 ÷ 10 = d/ 30 sec

same for t2= d/60 sec t3= d/180 kmph

total speed = total d/total time

= d/ d/30+d/60+ d/180

= d/ 10d/180

180/10= 18 kmph