A boatman goes 2 km against the current of the stream in 1 hr and goes 1 km along the current

A boatman goes 2 km against the current of the stream in 1...

Key Concepts

Effect of Current on Effective Speed

Understanding how the current affects effective speed is crucial. When moving with the current, the boat’s speed increases by the speed of the current, and when moving against it, the boat’s speed decreases by that amount. This differential effect leads to the formation of equations that can be solved to determine both the boat’s speed in still water and the current’s speed.

Distance-Time Relationship

This fundamental principle of kinematics states that distance is the product of speed and time. It is used to set up equations that relate the different segments of a journey, allowing one to solve for unknown quantities such as the time required to travel a given distance under varying conditions.

Relative Motion in Fluids

This concept involves understanding that when an object moves in a fluid medium like water, its effective speed is influenced by the motion of the medium. In scenarios involving a boat, the current can either add to the boat's speed when moving downstream or subtract from it when moving upstream, making it essential to consider the relative motion between the boat and the water.

Speed in Still Water

This key concept refers to the inherent speed of a boat in the absence of external influences such as currents. It represents the boat's capability under calm conditions and serves as a baseline from which adjustments are made when currents come into play.

Transcript

00:01 In this objective type cution given information is that is there is a river whose weight is given in the cution that is the width of the river is that is 2 kilometer and now in the cution it is saying that this river is flowing at a rate of given that means the speed of the river given that is river water that is equal to 2 km per hour and now in the cution saying that further information is given that is there is a boatman which can row the boat at the speed that is given that means boat of boats speed is given in steel water so in the speed in steel water that is given that is four kilometers per hour and in the question it is saying that this boat man goes two kilometers upstream and then comes back so now in the question it is asking that we have to find time taken by boatman to complete his journey so now you can see that there are four options given so after solving this question i will get the correct answer that means correct option that is option c so that means time will be is 80 minute so now i will give the explanation here so the reason behind the option c correct option that is c that is i consider first here i am using the data that is given that is saying that the board is moving two kilometers upstream and then after it it is coming back so i considered the in the upstream what speed of the board in river water will be written as that is 4 minus 2 kilometer per hour so simplify it then i will get that is the speed of the board with the way to river water that is 2 kilometer per hour and now it is coming back so that means it is moving in downstream direction so i can say that in that case the speed will be that is is equal to 4 plus 2 that means 6 km per hour so now in the question it is asking that we have to find total time taken by boatmen to complete his journey so i can see that total time will be that is taken that is equal to 2 divided by 2 plus 2 divided by 6 so i can see that now simplify it here this will show that the time taken during covering the two kilometers in upstream direction and this will show that the time taken by a boardman covering the two kilometer width of the river in downstream direction so we know that time formulae is that is t is equal to distance divided by speed so for upstream direction speed will be that is two kilometer and for downstream direction speed is which i had got in above step that is six kilometers so here i had put the value of speed at is six kilometer and distance will be for both case that is same is that is two kilometer so now simplify it then i will get time t total time t that is taken by boatman that is equal to four by three hours or i can say that in the minute it will be returned as that is 80 minute.

05:08 So that means in the hour that time will be that is 4 over 3 hour and in the minute it will be that is 80 minute.

05:20 Now next step is compare this result with the given option...

Please give Ace some feedback