Question

A man moves up on a 3 km long incline road with speed of 2 m/s,then on a 3 km level road with speed of 3 m/s and moves down on a 3 km long incline road with 6 m/s. Find the average speed of man.

Answer 1

Answer:

Average speed = total distance/total time

In this case, total distance = x+x+x=3x (they are unknown)

Time can be found using an equation

Time = distance / speed

So,

time1 = x/2

time2 = x/3

time3 = x/6

Hence total time = x/2+x/3+x/6 ( find lcm and add)

Total time = 6x/6

Ok now,

Average speed = total dist.÷total time

= 3x ÷ 6x/6

( divide fraction by multiplying with reciprocal)

= 3x × 6/6x

= 1 × 6/2

Average speed = 3m/s

Hope this helps.