Energy needed to launch a spaceship into Space

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Discussion Overview

The discussion centers on the energy required to launch a spaceship from a planet's surface to a height of 100 km. It involves calculations related to gravitational potential energy and the conditions of the spaceship upon reaching that height.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant presents the mass and radius of the planet, along with the mass of the spaceship, and asks for the energy needed to reach 100 km.
  • Another participant suggests calculating the potential energy at 100 km and raises a question about the assumed state of the spaceship at that height, proposing two scenarios: being in orbit or having zero velocity.
  • A later reply clarifies that the assumed state is that the spaceship has zero velocity upon reaching 100 km.
  • The same participant reiterates the zero velocity assumption and advises calculating potential energy, referencing a formula for further assistance.
  • The thread concludes with a reminder about forum rules regarding homework submissions and the need for the original poster to show their work.

Areas of Agreement / Disagreement

Participants agree on the assumption that the spaceship has zero velocity at 100 km, but there is no consensus on the approach to calculate the energy required, as the original poster's question is not fully addressed before the thread is locked.

Contextual Notes

The discussion is limited by the original poster's lack of effort in showing work, which is a requirement for homework-related queries in the forum. The potential energy calculation method is not fully explored due to the thread being locked.

IsakVern
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A given planet has a mass, M = 6.42*10^23 kg,
and radius, R = 3.39 * 10^6 m.

The gravitational konstant is G = 6.67*10^-11

A spaceship with mass m = 4000 kg is launched from the planets surface.

How much energy is needed to send the spaceship to a height h = 100 km above the planets surface?
 
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Hi Isak:

There are several ways to approach this problem. One way is to calculate the potential energy of the spaceship at the height of 100 km. That is the amount of energy that has to be added to get the spaceship to that height.

First, the problem statement is a bit unclear. What is the assumed state of the spaceship when it reaches a height of 100 km. Here are two possibilities:
a) the spaceship is in orbit around the planet.
b) the spaceship has zero velocity and will begin its fall back to earth.​

Hope this helps.

Regards,
Buzz
 
The assumed state of the spaceship is that it has zero velocity when it reaches 100 km.
 
IsakVern said:
The assumed state of the spaceship is that it has zero velocity when it reaches 100 km.
Hi Isak:

In that case I suggest you calculate the potential energy. You might find the following of some use. See the formula in the second box.
You may find the minus sign puzzling. If so, see what your textbook says about potential energy.

Regards,
Buzz
 
IsakVern said:
A given planet has a mass, M = 6.42*10^23 kg,
and radius, R = 3.39 * 10^6 m.

The gravitational konstant is G = 6.67*10^-11

A spaceship with mass m = 4000 kg is launched from the planets surface.

How much energy is needed to send the spaceship to a height h = 100 km above the planets surface?
Thread is locked.

@IsakVern -- All schoolwork problems go in the Homework Help forums, and you are required to show your work before we can offer tutorial help. Please re-post in the Homework Help, Introductory Physics forum, and fill out the Homework Help Template you are provided there. This includes sections on the Relevant Equations and your Attempt at a Solution.

@Buzz Bloom -- Please do not reply to misplaced schoolwork questions, especially when the OP shows zero effort in their post. Please click the Report link on their post instead, and ask the Mentors to deal with the post. Thanks.
 

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