Velocity of 84 kg Skier Jumper After Jumping 105 m Hill

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Homework Help Overview

The discussion revolves around calculating the velocity of a skier jumper after jumping from a height of 105 meters, starting from rest at the top of a 220-meter hill. The problem involves concepts of energy conservation, specifically the relationship between potential and kinetic energy.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the application of conservation of energy principles, questioning the original poster's calculations and emphasizing the importance of potential energy at the top of the hill. There are discussions about deriving kinetic energy from changes in potential energy.

Discussion Status

Some participants have provided guidance on considering the total energy of the skier at the top of the hill and the potential energy at the jump height. There is an ongoing exploration of the calculations and reasoning behind the energy transformations, with some participants expressing uncertainty about their answers.

Contextual Notes

Participants are discussing the implications of energy conservation without reaching a definitive conclusion. The original poster's calculations are questioned, and there is a focus on understanding the underlying principles rather than simply obtaining a numerical answer.

raman911
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A84 kg skier jumper starts fro rest at the top of a 220 m hill. What is the velocity of the skier jumper, if the jump is 105 m from the bottom of the hill.

My Proof:

m=84 KG
h=105 m
Eg=84kg*9.8N/kg*105m
Eg=86436J
so Eg=Ek
86436J=1/2*85*V^2
V=45..36m/s


Is that right or Wrong?
 
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It's wrong.

You must consider the energy he has at the top of the hill. Apply conservation of energy between that height and the height of the jump.
 
hage567 said:
It's wrong.

You must consider the energy he has at the top of the hill. Apply conservation of energy between that height and the height of the jump.
i didn't understand u
can u explain me?
 
Well for one thing, the kinetic energy the skier has at the time he reaches the jump must come from somewhere. The change in potential energy between the top of the hill and the jump is what will determine the kinetic energy at the jump. It will determine his velocity.

Why don't you think the potential energy the skier has at the top of the hill is important in finding out how much kinetic energy he has at the jump?
 
hage567 said:
Well for one thing, the kinetic energy the skier has at the time he reaches the jump must come from somewhere. The change in potential energy between the top of the hill and the jump is what will determine the kinetic energy at the jump. It will determine his velocity.

Why don't you think the potential energy the skier has at the top of the hill is important in finding out how much kinetic energy he has at the jump?
can u give me proof?
 
Tell me why you think it's wrong.

You have not shown any reasoning for your answer.
 
hage567 said:
Tell me why you think it's wrong.

You have not shown any reasoning for your answer.

because i am not sure about my answer
 
because i am not sure about my answer
Well you must have done your answer that way for some reason.

can u give me proof?
What kind of proof are you looking for? I'm not going to give you the answer if that's what you mean.

Have you tried to use my idea to solve this problem? What about it is giving you trouble?
Can you find the total energy of the skier when he is at rest at the top of the hill?
 
hage567 said:
Well you must have done your answer that way for some reason.


What kind of proof are you looking for? I'm not going to give you the answer if that's what you mean.

Have you tried to use my idea to solve this problem? What about it is giving you trouble?
Can you find the total energy of the skier when he is at rest at the top of the hill?

Eg=mghA
Eg=84kg*9.8N/kg*220m
Eg=181104J


Eg=mghB
Eg=84kg*9.8N/kg*105m
Eg=86436J


Eg=181104J-86436J
Eg=94668J

So Eg=Ek
94668JJ=1/2*85*V^2
V=47.47m/s


Is that right or Wrong?
 
  • #10
I would say that is right.
 

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