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lizzyb

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## Homework Statement

When it orbited the Moon, the Apollo 11 spacecraft 's mass was 13400 kg, and its mean distance from the Moon's center was 2.56393 X 10^6 m. Assume its orbit was circular and the Moon to be a unform sphere of mass 7.36 X 10^22 kg.

a) Given the gravitational constant G is 6.67259 X 10^-11 N m^2/kg^2, calculate the orbital speed of the spacecraft .

**DONE**

b) What is the minimimum energy required for the craft to leave the orbit and escape the Moon's gravitational field? Anser in units of J.

## Homework Equations

[tex] KE = \frac{1}{2}m v^2[/tex]

[tex]v_{esc} = sqrt{ \frac{2 G M}{R}}[/tex]

## The Attempt at a Solution

I did this: [tex] KE = \frac{1}{2} m_c v^2 = \frac{1}{2} m_c \frac{2 G M_m}{R} = \frac{G M_m m_c }{R}[/tex]

Where M_m is the mass of the moon and m_c is the mass of the spacecraft .

I plugged in the numbers but the anser was wrong. What else would they mean by energy required? Thanks.

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