Two Physics problems related to gravitational energy

[chroncile]

Homework Statement

1.) How fast must a rocket leave the Earth’s surface to reach a maximum height of 895 km above the surface of the Earth (assume the rocket is simply going straight up)?

The answer is 3920 m/s

2.) How fast must a rocket leave the Earth’s surface to reach an orbit with an altitude of 895 km above the surface of the Earth?

The answer is 8380 m/s

Homework Equations

E_G = -GMm / r

The Attempt at a Solution

For 1.)

E_k + E_G = E_k' + E_G'
0.5v² = GM / r
V = square root ((2 * G * 5.97*x10^24)/895000+6370000)
V = 10,470 m/s

For 2.)

I have no idea

 

[zhermes]

What you did for `1,' was you found the energy the rocket needed to end up with, then you figured out what velocity that corresponds to. You can do the same thing for `2,' just think: what's different about the final energy of the rocket in '2' as apposed to '1.'

 

[chroncile]

But I didn't even get the right answer in question 1.

 

[zhermes]

But I didn't even get the right answer in question 1.

Good point. What is the initial potential energy? Then what is the final?