Question

understand me upstream downstream sums and relative speed sums maths​

Answer 1

Answer:

Step-by-step explanation:

Understand me upstream downstream sums and relative speed sums maths​

UPstream Means  - going against stream

Means  Boat is moving against Water

So net speed of Boat = Boat Speed in Still water  - Stream (water) Speed

Hence in case of upstream net speed of boat will be lesser and more time will be taken by boat for same distance

Boat speed > Stream speed ( other wise boat would not be able to move further)

Downstream Means : going with the flow of  stream

Means  Boat is moving in the same direction as  Water

So net speed of Boat = Boat Speed in Still water + Stream (water) Speed

Hence in case of Downstream net speed of boat will be more and less time will be taken by boat for same distance

E.g :

A boat takes 2 hr in upstream & 1 hr in down stream

Please find stream speed & Boat Speed ration

Let say Boat speed = B km/Hr

Stream speed = kB  km/Hr

Distance = D Km

Time in upstream =  D/(B - kB) = 2

Time in Downstream =  D/(B + kB) = 1

(D/(B - kB) )/ (D/(B + kB))  = 2/1

=>  1 + k = 2 ( 1 - K)

=> 1 + k = 2 - 2k

=> 3k = 1

=> k = 1/3

Stream speed = B/3  = 1/3rd of Boat Speed