Solve a Skier Work Physics Problem on a 37.2° Slope – No Friction

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Homework Help Overview

The discussion revolves around a physics problem involving a skier being pulled up a slope, specifically focusing on the work required to move the skier along a frictionless incline at a constant speed. The problem incorporates concepts of work, gravitational potential energy, and kinetic energy.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply the kinetic energy formula to determine the work done, while others suggest incorporating gravitational potential energy into the analysis. There is a discussion about the implications of constant speed on kinetic energy and work done against gravity.

Discussion Status

Participants are actively engaging with the problem, questioning the assumptions made about kinetic energy and the relevance of gravitational potential energy. Some guidance has been offered regarding the correct application of energy concepts, but no consensus has been reached on the approach to take.

Contextual Notes

The problem is framed within the constraints of a homework assignment, emphasizing the need to consider both kinetic and potential energy without friction. The constant speed condition is also a focal point of discussion.

Momentum09
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A skier of mass 72.6 kg is pulled up a slope by a motor-driven cable. How much work is required to pull the skier 64.3 m up a 37.2 degrees slope? (assumed frictionless) at constant speed of 63.2 m/s.

For this question, would I just use the equation W = 1/2 mv squared?

Thank you so much!
 
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it is gaining height too, so PE=mgh is needed too
 
Last edited:
shramana said:
The velocity is not constant here.
I would use W=f.d
"...at constant speed of 63.2 m/s."

No--the equation K = (1/2)mv^2 is for kinetic energy. In your problem, the skier's kinetic energy remains the same because his speed remains the same. Only his gravitational potential energy (U = mgh) changes. Since the work done pulling the skier up does not go to changing his kinetic energy, it must have gone to changing his gravitational potential energy, right?
 
Last edited:
Oh I see! Thank you very much for your help!
 

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