How to calculate the height of a skier

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Homework Help Overview

The discussion revolves around calculating the height of a skier using principles of potential and kinetic energy, specifically in a frictionless context.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between potential energy and kinetic energy, questioning the validity of the original poster's calculations and the need for additional information such as the skier's velocity at the top of the hill.

Discussion Status

There is an ongoing examination of the calculations presented, with some participants suggesting that the original approach may not be sufficient without considering specific components of velocity and height. Multiple interpretations of the problem are being explored, particularly regarding the definitions of height and velocity.

Contextual Notes

Participants note the importance of distinguishing between the specific height labeled in the problem and the generic height used in the energy equations. There is also mention of needing more information about the skier's condition at the top of the hill.

JiJiasd
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Homework Statement


I want to calculate the height h of the skier in this figure
upload_2016-5-23_16-6-52.png


Homework Equations


potential energy and kinetic energy and there is no friction

The Attempt at a Solution



mgh = 0,5 *m*v^2
v=√ (2*g*h)

Now calculate the h when he goes up

mgh= 0,5 *m*√ (2*g*h)^2Am I doing right ?

Thanks
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JiJiasd said:
Now calculate the h when he goes up

mgh= 0,5 *m*√ (2*g*h)^2
What you got is an identity. You need more information of the person on the top of the hill to get his condition, such as velocity~
 
mgh = 0,5 *m*v^2
v=√ (2*g*h)

This is right but after this, only calculate with its vertical component (v*sin(28 deg)), when calculating h.
 
tommyxu3 said:
What you got is an identity. You need more information of the person on the top of the hill to get his condition, such as velocity~
These informations are enough, you don't need more!
 
You only got an identity, because you didnt calculate with the right component of speed.
 
thank you all
 
You need to be careful with 'h'. There is a specific height in the problem which is labelled h, and there is the generic h in the equation gh=v2/2. Don't get them mixed up.
First, find the velocity at the launch point.
 

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