How much time will it take for a log to arrive from point A, to point B?

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Homework Help Overview

The discussion revolves around a problem involving the time it takes for a log to float from point A to point B across a river. The context includes a boat's travel times in both directions, with the boat taking 5 hours to reach point B from point A and 7 hours to return, suggesting the influence of river flow on the travel times.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to clarify the problem setup, including the roles of the boat's speed and the river's flow. There are questions about the velocity of the boat and the width of the river, as well as the need for a diagram to better understand the situation. Some participants are exploring the relationship between the boat's speed and the river's flow.

Discussion Status

The discussion is ongoing, with participants seeking to confirm their understanding of the problem. There is a focus on identifying the variables involved, particularly the speeds of the boat and the river flow. Some guidance has been offered regarding the need for additional information, such as a diagram or specific velocities, to facilitate further analysis.

Contextual Notes

Participants note that the problem involves constant speeds and that the distances between points A and B are equal. There is uncertainty about the exact setup, including the direction of the river flow relative to the points.

HellgY
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A boat floats across this river, and back,
It takes 5 hours for it to reach point B, from point A, and then 7 hours to
return to point to point A from point B.

Naturally it's because not because the crew got tired on the way back,
but because the flow of the river, or it's angle which is pretty much more of the same.

the question is: How much time will it take for a log to arrive from point A, to point B?.

I believe the V0=Constant(The flow), otherwise that teacher would have said mentioned it.

i believe the equation is:
T2/V1=T1/V1-V0

The equation with all the numbers intact should look like that:

7/x=5/x-y

and there is another equation i can add, based upon the fact that the distances AB, and BA are the same.

T1*V1=T2*(V1-V0)

5x=7x-7y

does anyone have a clue how can i sole this correctly?, because my solution just doesn't seems correct at all.

{7/x=5/x-y
{5x=7x-7y*

or is it:
{5x=7x-yx
{x-y=5x/7*
 
Last edited:
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Welcome to the Forums,

Let me see if I've got this question straight in my head. A boat starts from point A to B, this takes five hours. Then the boat turns around and floats back to point A under no propulsion. You need to know how long it will take a log to float from A to B?

Have I got that about right? Is there a diagram?
 
Hootenanny said:
Welcome to the Forums,

Let me see if I've got this question straight in my head. A boat starts from point A to B, this takes five hours. Then the boat turns around and floats back to point A under no propulsion. You need to know how long it will take a log to float from A to B?

Have I got that about right? Is there a diagram?
It floats 7 hours back, with propulsion, apparently against the flow, or the angle of the river, or any constant force for that matter.

i need to calculate how quickly will a block of wood arrive from point A, to point B, driven by the flow of the river obviously, so what i need to find is V0, which is the speed of the river flow
 
HellgY said:
It floats 7 hours back, with propulsion, apparently against the flow, or the angle of the river, or any constant force for that matter.

i need to calculate how quickly will a block of wood arrive from point A, to point B, driven by the flow of the river obviously, so what i need to find is V0, which is the speed of the river flow
Do you have the velocity of the boat? Width of the river? I diagram would be very useful here. I am assuming that point A is downstream from point B.
 
Hootenanny said:
Do you have the velocity of the boat? Width of the river? I diagram would be very useful here. I am assuming that point A is downstream from point B.
It's the other way around, point B, is a downstream from point A.

I don't have the Velocity of the boat, Just the info i provided.

I'm suppose to find V1 and V0 with an equation, it isn't supposed to be a problem since we are dealing with constant speeds here
 

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