Solving Statement For Upstream And Downstream
Solving Statement For Upstream And Downstream
In these type of situations, while calculating upstream speed we subtract the speed of river from the speed of boat because the river is pushing the boat downwards even when the boat is moving upwards. Whereas when the boat is moving downstream the speed is calculated by adding the speed of river to the speed of boat.
Let the speed of a boat ( or a body) in still water be x km/h and that of stream be y km/h, then
Let the speed of boat in downstream and upstream be u km/h and v km/h, then
Speed of boat in still water
Illustration: A boat goes downstream from one point to another in 9 hours. It covers the same distance upstream in 10 hours. If the speed of the stream is 1 km/hr. Calculate the speed of boat in still water.
A. 15 Km/h B. 7.5 Km/h C. 19 Km/h D. 7 Km/h
Answer: C
Solution: Let the speed of boat in still water be x km/hr
Speed of stream = 1 km/hr
Speed upstream = x - 1 km/hr
Speed Downstream = x + 1 km/hr
As we know
Distance upstream = (x-1) X 10 = 10x - 10 Km
Distance Downstream = (x+1) X 9 = 9x + 9 Km
According to the question the distance is the same
10x-10 = 9x + 9
10x - 9x = 9+ 10
x = 19 km/hr
So the speed of boat in still water = 19 km/h
Hence the correct option is C.
Illustration: A motor boat whose speed in still water is 15 km/h, goes 40 km down stream and comes back in a total time of 6 hours. Find the speed of stream.
A. 5 Km/h B. 6 Km/h C. 15 Km/h D. 7 Km/h
Answer: A
A streamer goes downstream from one port to another in 4 h. It covers the same distance upstream in 5 h. If the speed of the stream is 2 km/h, find the distance between the two ports. | |||
| Right Option : D | |||
| View Explanation | |||
The boat which has a speed of 5 km/h in still crosses a river of width 1 km along the shortest possible path in 15 min. The velocity of river water (in km /h), h | |||
| Right Option : A | |||
| View Explanation | |||
A boat goes downstream from one point to another in 12 hours. It covers the same distance upstream in 15 hours. If the speed of the stream is 1 km/hr. Calculate the speed of boat in still water. | |||
| Right Option : B | |||
| View Explanation | |||
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