What has a higher total energy?

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Homework Help Overview

The discussion revolves around understanding the total energy of a satellite in different orbits, specifically comparing a 40.0 kg satellite in a 177 km orbit versus a 144 km orbit. The participants explore the implications of gravitational potential energy and kinetic energy in the context of orbital mechanics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between orbital radius and total energy, referencing equations for potential and total energy. There is uncertainty about how to articulate the differences in energy in terms of kinetic and potential energy. Questions arise regarding the role of friction in the context of the problem.

Discussion Status

The discussion is active, with participants questioning assumptions about friction and seeking clarity on the relationship between total energy and orbital radius. Some guidance has been offered regarding the interpretation of energy values, but no consensus has been reached on the explanation of the energy differences.

Contextual Notes

Participants note that friction is mentioned but not included in the problem statement or relevant equations, leading to questions about its relevance to the discussion.

jakeginobi

Homework Statement


Why does a satellite that has a 40.0kg mass in its 177km orbit has a total energy larger than its 144 km orbit?

Homework Equations


Ep = -GMm/r, Et = -GMm/2r

The Attempt at a Solution


I figured from using the Et equation, the greater the radius the bigger the value, but I don't know how to explain it in terms of potential energy and kinetic energy. Also its path is a circular orbit and there's friction involved
 
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jakeginobi said:

Homework Statement


Why does a satellite that has a 40.0kg mass in its 177km orbit has a total energy larger than its 144 km orbit?

Homework Equations


Ep = -GMm/r, Et = -GMm/2r

The Attempt at a Solution


I figured from using the Et equation, the greater the radius the bigger the value, but I don't know how to explain it in terms of potential energy and kinetic energy. Also its path is a circular orbit and there's friction involved

You have a negative value for ##E_t##, which I assume is kinetic energy.
 
PeroK said:
You have a negative value for ##E_t##, which I assume is kinetic energy.
Total energy.

Basically: it takes energy to move the satellite to infinity. More energy than the kinetic energy (namely twice as much).

The further out you start, the easier it becomes ==> total energy is larger at 177 than at 144 km up.
 
@jakeginobi If you have the total energy, what's your question?
 
jakeginobi said:
there's friction involved
Not in the problem statement, not in the relevant equations.
Together with PeroK, I wonder how we can best help you.
 

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