Calculating Change in Gravitational PE for 70 kg Skier

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Homework Help Overview

The discussion revolves around calculating the change in gravitational potential energy for a skier using the given parameters of mass, lift length, and angle. The focus is on understanding the relevant equations and their components in the context of gravitational potential energy.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply the equation "Ef * s = mas" but expresses confusion about its validity and the role of each symbol. Participants question the meaning of the symbols and the structure of the equation, particularly regarding the multiplication and the relevance of displacement.

Discussion Status

Participants are actively engaging in clarifying the meanings of the symbols in the equation and exploring the implications of the relationships between work, force, and displacement. There is an ongoing examination of whether the equation is balanced and how it relates to the concepts of energy and force.

Contextual Notes

There appears to be some uncertainty regarding the application of the equations and the definitions of the variables involved, which may affect the understanding of the problem. The discussion is focused on the interpretation of the equation rather than its application to find a solution.

rcmango
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Homework Statement



A 70.0 kg skier rides a 2700 m long lift to the top of a mountain. The lift makes an angle of 14.3° with the horizontal. What is the change in the skier's gravitational potential energy?
in Joules


Homework Equations





The Attempt at a Solution



I can't seem to find why Ef * s = mas
does not work?

i've tried using the equation for an answer and it doesn't seem to give me the right answer.
 
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What is the meaning of the symbols in "Ef * s = mas", especially the *?
 
E = "work done by net ext. force

s = displacement

m = mass
a = acceleration
 
Thanks :-)

The f and the * ?
 
f = force and * = multiplication
 
Thanks :-)

* = multiplication, the same as between E and f, m and a, and a and s?

If that's correct then the equation could be rewritten as
Efs = mas
which would be a strange equation because the s is useless; the equation is equivalent to
Ef = ma
and that can't be right because E, work/energy, is force times distance and ma is force so the equation would not be balanced -- the units would not be the same on each side. It would be saying
force x distance x force x distance = force
 

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