- #1

Jared

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## Homework Statement

The gravitational potential energy of a certain rocket at the surface of the Earth is -1.9x10^12 J. The gravitational potential energy of the same rocket 300km above the Earth's surface is -1.8x10^12 J. Assume the mass of the rocket is constant for this problem.

A) How much work is required to launch the rocket from the surface of the Earth so it coasts to a height of 300km? (starting and ending at rest, no orbit, just straight up and down):

**Found to be deltaU= -1.8x10^12- -1.9x10^12= 1x10^11 J. (this mas be wrong but teacher said to just make corrections).**

B) What additional Kinetic energy is required to put the rocket into a circular orbit?

**Found to be KE= 1/2(1x10^11)= 5x10^10 J**

Here is where I have trouble.

C) How much extra energy is required for the rocket to reach escape velocity from this orbit?

## Homework Equations

V_esc=(2GM/R)^1/2

I'm sure I am missing something. Also sure it's really easy just blanking on it.

## The Attempt at a Solution

I get V_esc= 10927.99m/s but then I go to use the equation for KE=1/2MV^2 but I don't know how to find the mass of the rocket because we were told it was constant. So I'm just not sure if I should be using a different equation or what.