HELP ON A WORK PROBLEM CAN'T DO IT BY MYSELF SNIFF SNIFF.:cry:

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Homework Help Overview

The problem involves calculating the work done in lifting a uniform ladder from a horizontal to a vertical position. The subject area pertains to mechanics and potential energy concepts.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the work done using the formula for gravitational potential energy, suggesting that lifting the center of mass is key. Some participants affirm this approach, while others elaborate on the relationship between work and potential energy for the entire ladder.

Discussion Status

The discussion is active, with participants exploring the relationship between work and potential energy. Some guidance has been offered regarding the calculation of potential energy in relation to the ladder's mass and center of mass position.

Contextual Notes

Participants are navigating the assumptions related to the ladder's uniformity and the relevance of kinetic energy in this scenario.

Min_Shin
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a uniform ladder of mass 12kg is 4.6m long. if it is lifted from a horizontal to a vertical position, how much work is done

i just thought because i have to lift the centre of the mass, i'd have to do mgh with h being 2.3m. I think i am sure that i don't have the right answer. Sniff.. help please!
 
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I think you are correct.
 
HAHA... oh... thanks.
 
Last edited:
The work must equal the potential energy increase for the ladder (since there isn't any kinetic energy relevant for this problem).

But the potential energy increase for the WHOLE ladder, is simply the ladder's mass multiplied with g and the C.M's position, since the gravitational potential energy is linear in the vertical position coordinate.
 

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