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Work and force 
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#1
Apr1408, 02:39 PM

P: 90

1. The problem statement, all variables and given/known data
a 50 kg diver steps off a diving board and drops straight down into the water. The water provides an upward average net force of 1500 N. If the diver comes to rest 5.0m below the water's surface, what is the total distance between the diving board and the diver's stopping point under water? 2. Relevant equations 3. The attempt at a solution the total force would be FnFg which is 150050*9.81=1009.5N W=1009.5*(x+5) i am completely lost on what to do next. please give me a clue or something. 


#2
Apr1408, 02:58 PM

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#3
Apr1408, 03:01 PM

P: 90

oo it wud b fg which is 50*9.81 which is 490.5 . but that doesnt help.



#4
Apr1408, 03:48 PM

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Work and force
Sure it helps. There are several ways to solve this kind of problem. One way would be to compare the work done on the diver before he hits the water to the work done on him after he hits the water. After all is said and done, what must the total work (by all forces) be on the diver?



#5
Apr1408, 04:41 PM

P: 90

well you dont know the distance so you cannot find the total work done.



#6
Apr1408, 04:44 PM

Sci Advisor
P: 2,193

Think what total work means in reference to his original state (position and velocity) and final state.



#7
Apr1408, 05:37 PM

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#8
Apr1408, 06:25 PM

P: 90

you cannot because you would have two unsolved, the work net and the distance.



#10
Apr1408, 07:15 PM

P: 90

W=1009.5*(x+5) and W=490.5x
are those two equations correct? 


#11
Apr1408, 07:26 PM

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The diver travels a distance x before hitting the water. What net force acts? What's the net work? Is it positive or negative? The diver travels 5 m under the water. What net force acts? What's the net work? Is it positive or negative? What must those two work contributions add to? (Hint: What's the change in KE?) 


#12
Apr1408, 07:36 PM

P: 90

well when he is in water the work he does would be 1500N*5m because thats the distance he z traveling and the net force is 1500. so the work done would be 7500J.
The work he does under water would not be the same as above water would it? 


#13
Apr1408, 07:49 PM

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#14
Apr1408, 07:56 PM

P: 90

the work done above water would be negative while the word done below water would be positive. but how can both of them have the same magnitude? that's the part i don't understand.



#15
Apr1508, 04:48 AM

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