The Change In Gravitational Potential Energy?

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Homework Help Overview

The problem involves a snowball being fired from a cliff, requiring the calculation of work done by gravitational force and changes in gravitational potential energy during its flight. The context is rooted in gravitational potential energy concepts within physics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of gravitational potential energy equations and the implications of the gravitational force being conservative. There are attempts to clarify the relationship between initial and final positions in the context of work done.

Discussion Status

Some participants are exploring different interpretations of the equations related to gravitational potential energy. Guidance has been offered regarding the conservative nature of gravitational force, which may help in understanding the problem better. However, there is no explicit consensus on the correct approach to part b).

Contextual Notes

The original poster expresses uncertainty about the calculations for part b) and mentions specific values for parts a) and c), indicating a potential misunderstanding of the concepts involved. There is a reference to a textbook problem, which may impose specific constraints or assumptions relevant to the discussion.

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Homework Statement


A 2.40 kg snowball is fired from a cliff 10.4 m high. The snowball's initial velocity is 19.3 m/s, directed 42.0° above the horizontal. (a) How much work is done on the snowball by the gravitational force during its flight to the flat ground below the cliff? (b) What is the change in the gravitational potential energy of the snowball-Earth system during the flight? (c) If that gravitational potential energy is taken to be zero at the height of the cliff, what is its value when the snowball reaches the ground?

Homework Equations


Gravitational Potential Energy = mgh
or = (mgd)cos(theta)

The Attempt at a Solution


I have concluded that the answers to parts a) and c) are both positive and negative 245 Joules respectively. I am just having a little trouble with part b). I used the (mgd)cos(theta) equation and I also attemped to change its sign and both times I was wrong. This is problem 6, chapter 8 of Halliday's The Fundamentals Of Physics 8th edition.
 
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Bump for despirately not knowing how to solve a problem...
 
The gravitational force is conservative. The work done by it depends only on initial and final positions of the object.. That should help you a lot.
 
K + U = K_o + U_o
 

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