Book answer wrong? Work = Fd question. Space Shuttle entry

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Homework Help Overview

The discussion revolves around a physics problem related to the energy transfer of the space shuttle during its flight path and the calculation of the force applied by the atmosphere. The original poster questions the accuracy of the book's answer regarding the force calculation based on the given energy and distance.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the calculation of force using the work-energy principle and express doubts about the book's answer, suggesting a potential error in the distance used. They also explore the implications of the shuttle's flight path and its relation to the distance from the atmosphere to the Earth's surface.

Discussion Status

The conversation is ongoing, with participants examining the assumptions about the flight path distance and the nature of the shuttle's descent. Some guidance on the calculation method has been offered, but there is no explicit consensus on the correctness of the book's answer or the assumptions made.

Contextual Notes

Participants note discrepancies in the distance values provided in the problem and question the validity of the 8000 km flight path in relation to the shuttle's actual descent from orbit.

Barclay
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Homework Statement


The space shuttle has 8.45 x 10(to the power12) joules of energy transfer over an 8000km flight path. What force is applied by the atmosphere?

Homework Equations


The book answer is 1.06 x 10 (to the power nine) Newtons.

I think the book answer is wrong. They've shown the calculation as 8.45 x 10(to the power12) / 8 x 10 (to the power 3).

I think the mistake is that they should have used the value 8 x 10 (to the power 3)

The Attempt at a Solution


[/B]
Work = Force x distance

Force = 8.45 x 10(to the power12) / 8000 x 10 (to the power 3).

Force = 1056250 N = 1.06 x 10 (to the power 6)

Please advise. This is High School physics
 
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Yes, they appear to be off by 3 orders of magnitude.

By the way, you can use the x2 symbol on the toolbar to get exponents: 103.
 
DrClaude said:
Yes, they appear to be off by 3 orders of magnitude.
By the way, you can use the x2 symbol on the toolbar to get exponents: 103.

Thanks ... so my answer Force = = 1.06 x 106 is correct. I was thinking does the shuttle really have a flight path of 8000km as the question says? The distance from atmosphere to Earths surface is much less isn't it ?? Had a quick look on internet and looks like 400 km
 
Barclay said:
Thanks ... so my answer Force = = 1.06 x 106 is correct. I was thinking does the shuttle really have a flight path of 8000km as the question says? The distance from atmosphere to Earths surface is much less isn't it ?? Had a quick look on internet and looks like 400 km
Yes, but does the shuttle come to a complete stop in outer space and then fall straight to the ground? That's the only way the distance on re-entry becomes 400 km.
 
SteamKing said:
Yes, but does the shuttle come to a complete stop in outer space and then fall straight to the ground? That's the only way the distance on re-entry becomes 400 km.

Oh I see ... the shuttle does not just drop onto Earth perpendicular to a point on the surface. It flies in an orbit around the Earth so the path is 8000 km
 
Barclay said:
Oh I see ... the shuttle does not just drop onto Earth perpendicular to a point on the surface. It flies in an orbit around the Earth so the path is 8000 km
You got it, except the Shuttle is technically no longer in orbit.

The great length of this path is designed so that the Shuttle bleeds off the kinetic energy from orbiting the Earth and slows down to a manageable landing speed by the time it reaches its landing field. The Shuttle is not powered after re-entry to the atmosphere and glides to its final destination.
 

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