a body covers a distance with a speed of 30 kmph and returns the same distance with a speed of 40 kmph. find the average speed
Answers
Answer:
Average Speed. The speed of an object isfound out by dividing the distance that the object covers by the time in which the object takes to cover this distance. If 'D' is thedistance traveled in some time 'T' then thespeed of the object for this journey or 's' is equal to s = D/T. This is the simplest case.
Explanation:
Let the distance covered in one trip be x.
Speed, V1 = 30km/h
Speed V2 = 40km/h
Distance covered is same in both trips.
Speed = Distance / Time
» Time = Distance / Speed
Time taken in first trip, T1 = x/30
Time taken in second trip, T2 = x/40
Average speed =
Total Distance /Total Time
v = (x + x) / (x/30 + x/40)
v = 2x / (70x/1200)
v = 2x × 1200/70x
v = 2400/70
v = 34.285 km/h
Derived formulas,
If distance covered is same, time is different, then average speed =
(2×V1×V2)÷(V1+V2)
If time taken is equal, distance is different, then average speed =
(V1 + V2) ÷ T
By the way, the above method is the most appropriate if you don't want to memorize the formulas. But doing the method is time consuming so I would say to learn formula