Calculating Maximum Height in Projectile Motion for an Olympic Long Jumper

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Homework Help Overview

The discussion revolves around calculating the maximum height achieved by an Olympic long jumper during a jump, given the horizontal distance and initial velocity. The problem involves concepts from projectile motion.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the initial vertical velocity and its impact on the maximum height calculation. There are attempts to apply kinematic equations, with some questioning the assumptions made about initial conditions and time of flight.

Discussion Status

Participants are actively exploring different interpretations of the initial velocity and time variables. Some have provided calculations, while others have suggested reevaluating assumptions. There is no clear consensus on the correct approach yet.

Contextual Notes

There is a noted confusion regarding the initial vertical velocity and the time at which maximum height occurs. The participants are working under the constraints of the problem as stated, without additional information.

atbruick
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Homework Statement


An Olympic long jumper is capable of jumping 8.5 m. How high does he goes? (Assuming he lands standing upright). His initial horizontal velocity is 9.7 m/s.

Before it asked his height, I found that the time he is in the air is 0.88 seconds.


Homework Equations


Y=Yinitial+Vyinitial*t-.5at^2


The Attempt at a Solution


Since Y is the maximum height, I just tried plugging in numbers for the symbols in the rest of the equation. Yintial was 0, Vyintial was 0, t was 0.44 because max height is in the middle, and a is -9.80m/s2. I got an answer of 9.5, which was wrong. I have a feeling I'm substituting incorrectly but can't figure out what.
 
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The assumption that Vy initial is zero is wrong. If it was zero, then the maximum height would be zero.

It seems to me you would have to use Vf = Vi + at to find Vi before doing your vertical distance calc.
 
Ok, so hoping my calculations for Vy initial are correct, I got 18 m/s, then I tried finding the maximum height and got 20 meters with time as 0.88, which was incorrect. So I thought I should put in time as 0.44 because that is when he will be at maximum height and got 8.9 and that was incorrect too. Not sure what to do now.
 
I think 18 is much too large for Vy initial. It would be more helpful if you showed what you did than what the answer was. I used
Vf = Vi + at
-Vi = Vi -9.8*t
2*Vi = 9.8*0.88
 

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