Rivers Boats and streams

In Boats and stream based problems,we need to calculate either speed or time to reach some point either upstream or downstream.
Rivers Boats and streams


In water,the direction of the flow is downstream and opposite direction is upstream.



Speed of boat in still water is u and speed of stream is v then:
Speed upstream:u-v
speed downstream:u+v


If speed upstream is a and speed downstream is b then:
speed in still water is (a+b)/2
the rate of flow of the stream is (a-b)/2

*********************************************************************************
Rivers Boats and streams
Example1:
To find the rate of the stream, a man sails in a boat from location A to B at a speed of 12kmph and from B to A at a speed of 6kmph, find the rate of stream and speed of the boat in still water.
solution:
u=12
v=6
speed in still water=(a+b)/2 =(12+6)/2=9
rate of flow of stream=(a-b)/2=(12-6)/2=3
Rivers Boats and streams

Example2:
A man wants to reach from point A to B(distance b/w them is 6 km), he has two options to reach the destination the first one is to sail in the river and the second one is cycling.
A local person said that stream flow is 12kmph(A-B direction).If he uses a bicycle he can reach B at 12kmph.find the best suitable option for him.
solution:
If he sits in a boat it sails at 12kmph without any work and if he uses bicycle he can go at 12kmph but he has to work a lot hence boat could be the best possible option.





Comments

Post a Comment

Popular posts from this blog

Calendar problems solving tips without any formula

Image
If you keenly observe the calendar, if today is Wednesday same date of the next year will be Thursday (if there is no Feb 29 in between) and Friday(if Feb 29 comes) but what if someone asks you to find the day of a given random date? I have found many people asking calendar problems formula. there is no need for any formula as you can do it all by yourself with calendar problem aptitude tricks.  So here is a simple procedure with which you can simply find the day of a given date. Before learning the complete procedure, let me introduce a few basic terms required to solve these type of problems. Calendars are prepared based on the earth's orbit around the sun and it is designed it in a way that every orbit is equivalent to 1 year. with some fraction of the day left out for a year and this fraction is adjusted with the help of leap days. Most of the people think that every 4th year is a leap year but this is not true if one considers every 4th year as a lea
Read more

Numbers and number systems

Image
In this post let us clearly know about the classification of the number system.before classifying numbers let us know about numbers and number systems.  what is a number? =>A number can be defined as a group of digits which have some value. what is a number system? =>The systematic way in which numbers are organized
Read more

Direction and distance

Image
In the direction based problems, we should generally determine the direction or distance if a person travels in a path with many lefts or rights and turns in a certain direction. Basic things which we need to keep in our mind while solving direction based problems includes the direction compass. If we measure the angles between directions, the angle between two successive directions is 90 degrees.
Read more