Find the initial velocity of a man falling in a boat

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Homework Help Overview

The problem involves a scenario where a man named Warren falls into a canoe from a height of 0.95 m. The discussion centers around determining the initial velocity of Warren as he impacts the canoe, considering the masses of both Warren and the canoe, as well as the distance they move after the fall.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of final velocity based on distance and time, while questioning the implications of the collision between Warren and the canoe. Some raise concerns about the specifics of the fall, such as whether it was vertical or at an angle, and the relevance of momentum conservation in this context.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the problem statement and the exact nature of the question being asked. There is a recognition of ambiguities in the wording of the problem, particularly regarding what is meant by "initial velocity" and the lack of a complete question. Some participants suggest that additional information may be necessary to arrive at a definitive answer.

Contextual Notes

There are noted constraints regarding the clarity of the problem statement, with participants expressing frustration over the perceived difficulty of the question and the lack of explicit details. The discussion highlights the importance of understanding the context of the fall and the mechanics involved in the collision.

Brady Aucoin
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Thread moved from the technical forums, so no HH Template is shown.
Warren falls over his tackle box and lands in a canoe 0.95 m below the side of the dock. Warren's mass is 70 kg and the canoe has a mass of 72 kg. Warren and the canoe move 1.73 m away from the dock in 1.005 seconds.

relating equations are
Vi = Vf - at
v = d/t
A = change in velocity/time interval

Work
I was thinking that I would need to take the the velocity from the end of the problem which is 1.73 m /1.005 s = 1.72 m/s. I think that is my Vf, i just want to make sure that is correct. Because if it was the Vf i still need to find the acceleration. Any help would be appreciated.
 
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What happens when Warren hits the canoe? Have you studied collisions?
 
Brady Aucoin said:
Warren falls over his tackle box and lands in a canoe 0.95 m below the side of the dock.

As per the event pl. state what you wish to know? apart from given data the 'falling' part is important -how he fell verically down or in a curved path?
 
drvrm said:
As per the event pl. state what you wish to know? apart from given data the 'falling' part is important -how he fell verically down or in a curved path?
That is the exact question and all of the information, it only asks me to find the initial velocity, that's why i am coming here because i was hoping some people who are good a physics can help me get past this question.
 
Brady Aucoin said:
it only asks me to find the initial velocity,

i hope it is initial velocity of the canoe?

Brady Aucoin said:
Warren's mass is 70 kg and the canoe has a mass of 72 kg. Warren and the canoe move 1.73 m away from the dock in 1.005 seconds.

it appears that there was collision of the two and momentum of canoe changed- the man was on the tackle box and he fell and provided a push to the boat
he fell through a height h so he must have transferred his potential energy to a velocity of fall and ultimately his momentum to the canoe.
so now you can proceed using conservation of momentum.

if you are a physics student you know momentum is a vector so one will ask at what angle he fell and hit the canoe?

Brady Aucoin said:
i was hoping some people who are good a physics can help me get past this question.

well one can not fill in the missing words 'of a question' that will be 'guessing' the thing actually happening.
 
Brady, please provide the complete and exact question, word for word, as given to you.
 
haruspex said:
Brady, please provide the complete and exact question, word for word, as given to you.
it's sad to say that is the entire problem, i constantly struggle in the class but i don't think it is because of the subject, the highest grade on our most recent test was a 70%, i don't usually go online asking for help but when it comes to this worksheet i really am in disbelief on how hard it is, I'm a senior in a CP physics class, i usually am a 3.5 student and i study my a$$ off for this subject and still can't keep a C. If it really is that bad i'll just confront her about it
 
What do you mean "entire problem"? As written in the OP there is no question asked.
 
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nasu said:
What do you mean "entire problem"? As written in the OP there is no question asked.
To amplify on this, when you put part of the problem statement in the title of a message, you should still include that portion in the body of the message. The body should be complete and able to stand on its own. It must not depend on the thread title for context or for details.
 
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  • #10
Brady Aucoin said:
it's sad to say that is the entire problem,
ok.
Here are the ambiguities that I see. What moment in the process does "initial" refer to? Before he tripped, nearly zero. So probably it means just before he hit the boat.
What does velocity refer to? It's often used, sloppily, just to ask for speed. If so, is it the total speed (which we could get from the height fallen, if only we knew the height of the man's mass centre before he fell) or just the horizontal component (which we can get from conservation of momentum and the speed of the boat after landing)?
In each of those cases, we only need some of the information given. If it really means velocity, as in magnitude and direction, then we need to figure out both of those.
Putting all that together, my guess is it really is asking for velocity, but you don't quite have enough information. You will have to assume the height given is the height through which the man's mass centre falls.
 

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