hi
I'm a current vce physics student so my methods/answers might be wrong. (I also just started learning latex two days ago so the formatting probably looks sus)
1) I would use
and sub in r=400 000 + 6.37*10^6 m (radius from surface+radius of earth), and M=mass of earth.
2) I would use
and sub in the same values I did in question 1. I think the graph would look like a truncus.
3) I didn't draw the graph in question 2 but I think the answer would vary depending on the graph scale used.
4) I would estimate the area under the graph in question 2, then multiply by 3000kg. Because something like
5) I have the change in kinetic energy from question 4, so I would use
and solve for v, then add 500m/s to find the final speed.
Hopefully this is somewhat helpful. I'm not sure if this is the right way to do these questions, and would appreciate any corrections.