Classical Mechanics: Linear movement against a constant force

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The discussion revolves around solving an integral related to a boat slowing down due to a resistive force. The user encounters difficulties with the integral in part c) of their homework, specifically regarding the expression for the force. There is a suggestion that the force might need to be adjusted to F=-b(e^{cv}-1) for proper formulation. Additionally, guidance is provided on tackling the integral by considering the form of the function involved. The conversation emphasizes the importance of correctly setting up the integral to facilitate solving the problem.
cemtu
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Homework Statement
A boat with initial velocity Vo starts to slow down by the resistive force F=-b(e^cv) (b and c are constants v is the velocity of the boat) by water when the engines are stopped.
a)Find the velocity v(t)
b)Find the time required for the boat to stop
c)Find the distance until the boat completely stop
Relevant Equations
## F = mdv/dt = -b(e^c)^v ##
I solved this question until the end of the "c)Find the distance until the boat completely stop"
However I can not solve the integral I encounter in the solution of the last part of c).

Would you please check for math and maybe my mistakes and tell me what to do? Here:
 

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Can you identify the mistake in this line?
1577911726789.png
 
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Likes cemtu
Awful sign and writing mistakes. :D
Thank you mister TSny! However, correcting these writing mistakes does not help me solve the integral at part c) of my question. :D
 
cemtu said:
Homework Statement:: A boat with initial velocity Vo starts to slow down by the resistive force F=-b(e^cv)
Are you sure this is a correct statement of the problem? Note what happens at v=0.
Is it perhaps a force ##F=-b(e^{cv}-1)## ? But that would make for a very nasty integral.
 
Last edited:
cemtu said:
solve the integral at part c)
I assume you now have an integral of the form ##\int \ln(At+B).dt##. When faced with ##\int f(t).dt## which you don't know, a good place to start is tf(t). Differentiate that to see what you get and what adjustments you need to make.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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