a boat goes 6 km an hour in still water , but takes thrice as much time is going the

N

Namunah

New member
same distance against the? a boat goes 6 km an hour in still water , but takes thrice as much time is going the same distance against the current . The speed of the current ( in km /hr ) is .
 
»

»[Brain]«»[Waves]«1

New member
Let the velocity of the boat be v km/h and velocity of the current be u km/h.

When the boat goes in still water, its velocity is v=6 km/h.

When the boat goes against the current, its velocity is v-u=(6-u) km/h.

For distance S, time taken in still water to cover the distance = S/6 seconds.

For same distance S, time taken while going against the current = S/(6-u) seconds.

According to given, S/(6-u) = 3*(S/6)

=> 1/(6-u) = 1/2
=> 6-u = 2
=> u=4 km/h.

So, the speed of the current is 4 km/h.
 
»

»[Brain]«»[Waves]«

New member
Let the velocity of the boat be v km/h and velocity of the current be u km/h.

When the boat goes in still water, its velocity is v=6 km/h.

When the boat goes against the current, its velocity is v-u=(6-u) km/h.

For distance S, time taken in still water to cover the distance = S/6 seconds.

For same distance S, time taken while going against the current = S/(6-u) seconds.

According to given, S/(6-u) = 3*(S/6)

=> 1/(6-u) = 1/2
=> 6-u = 2
=> u=4 km/h.

So, the speed of the current is 4 km/h.
 
Top