Calculating Work with Kinetic Energy in Orbit

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SUMMARY

The discussion focuses on calculating the work done by an external force on a 62 kg satellite transitioning from an orbit radius of 3.3 x 107 m to 7.7 x 106 m. The initial approach involved integrating the gravitational force, represented by the equation F = GMm/r2, leading to an incorrect work calculation of -2.46 x 109. The correct method requires incorporating kinetic energy, as the satellite's velocity increases in a lower orbit. The relationship GPEfinal + KEfinal = GPEinitial + KEinitial + Workexternal is essential for accurate work calculation.

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  • Understanding of gravitational potential energy (GPE)
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Homework Statement


A 62kg satellite orbits the Earth with a radius of 3.3*10^7 m. A net external force acts on the satellite to an orbit of 7.7*10^6 m, what work must the external force do?


Homework Equations


W = integral of F with respect to d


The Attempt at a Solution



Integrate F which in this case is GMm/r^2 which becomes -GMm/r, then plug in the radii. However, the answer that I got was -2.46*10^9, which is incorrect.
 
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You need to include the kinetic energy as well, because the velocity of the satellite
in a lower orbit will be bigger
 
willem2 said:
You need to include the kinetic energy as well, because the velocity of the satellite
in a lower orbit will be bigger

How would I include the kinetic energy?

Would I approach it as this?

GPE = gravitational potential energy
KE = kinetic energy


GPEfinal + KEfinal = GPEinitial + KEinitial + Workof external force ?
 

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