Freefall, is the answer really 20 ?

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Homework Help Overview

The problem involves a lead ball dropped from a height of 5.0 m into a lake, where it sinks at a constant velocity after hitting the water. The original poster attempts to calculate the total depth of the lake based on the time it takes to sink.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster uses a kinematic equation to find the velocity of the ball and calculates the depth based on the sinking time. Some participants question the clarity of the problem statement, particularly regarding the timing of the 3 seconds and whether it refers to the sinking phase.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the problem's wording and expressing confusion about the timing involved. There is no clear consensus on the interpretation of the question or the calculations presented.

Contextual Notes

Participants note potential ambiguity in the problem statement, particularly regarding the duration of the sinking and the initial conditions of the drop. The original poster's calculations yield a depth of 29 meters, while a provided answer suggests 20 meters, leading to further questioning.

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Homework Statement



A lead ball is dropped into a lake from a diving board 5.0 m above the water. After entering into the water it sinks into the bottom with a constant velocity which it hit the water for 3 seconds. and hits the bottom of the lake. How deep is the late ?

Homework Equations


Vf ² - Vi ² = 2as


The Attempt at a Solution



Well I just used this equation and I get a velocity of 9.89 which I find odd. I think it should take less then 1 second to hit the water.

I get an answer of 29 meters by finding out the velocity and multipling by 3 seconds.
Altho in the answers it says 20.
 
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You should be right. It didn't say 2 seconds?
 
did you post the question exactly? Is the 3 seconds after it hits the water? I'm confused by this part:

"which it hit the water for 3 seconds. and hits the bottom of the lake"
 
show more steps, i don't like the equation you used
 

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