Power involved in running upstairs

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Homework Help Overview

The discussion revolves around a physics problem involving a student jogging upstairs, focusing on the calculation of power expended against gravity while ascending a vertical distance of 17.6 m over 65 seconds.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between power, work, and gravitational force, questioning how to incorporate gravity into their calculations. There are discussions about the physical implications of gaining height and potential energy during the ascent.

Discussion Status

Participants have engaged in a productive dialogue, with some offering insights into the concepts of potential energy and the nature of work against gravity. There is an acknowledgment of the complexity of the problem, but no explicit consensus has been reached regarding the final calculations.

Contextual Notes

Some participants express uncertainty about the mathematical incorporation of gravitational force and potential energy, indicating a need for clarification on these concepts within the context of the problem.

Capncanada
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Homework Statement



A 65 kg student jogs upstairs from the first floor to the sixth, a vertical distance of 17.6 m, in 65 s. Find the power the student expends working against gravity (In kW.)

Homework Equations



F=m*A
W=F*d
P=W/t

The Attempt at a Solution



Tried solving here but didn't know how to incorporate gravity into this, got a crazy answer.
 
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So power is in Watts, which is Joules per Second. What does the student gain when (s)he runs upstairs?
 
The student would gain height as they climbed.
 
But why is it hard work going upstairs, but not down them?
 
Because gravity is weighing down on you as you ascend. I understand it physically, but I don't know where to incorporate g mathematically.
 
If you lift a weight up into the air, what (other than height) are you giving it? If you drop it, it gains kinetic energy, but where does that energy come from?

Sorry that it appears I'm taking a really roundabout route with this; I'm trying to get you to come up with the answer!
 
It gains potential energy as it gains height, so can I use the law of conserved forces?
 
Excellent, yes it does. So you should be able to calculate how much energy the student has gained, and you know how long it took...
 
Got the right answer, thank you. That was a lot simpler than I thought it was... lol
 
  • #10
These things often are!
 

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