Space- need help with question please (1 Viewer)

[LoneWolf1990]

I was just revising from my Dot Point textbook and I need help with this question that even stumped my tutor:

'Calculate how far an astronaut would need to be away above the Earth in order for his weight to be 0.01 his weight on the Earth's surface.'

How do I do this???

 

[namburger]

I was just revising from my Dot Point textbook and I need help with this question that even stumped my tutor:

'Calculate how far an astronaut would need to be away above the Earth in order for his weight to be 0.01 his weight on the Earth's surface.'

How do I do this???

On a previos post not long ago

W = mg
g = GM/r^2

Solving simultaneously gives you W = GMm/r^2
N.B. M is mass of planet and m is mass of object

W = 9.8m is the weight of the object on surface
0.01 of its W = 0.098m

Therfore
0.098m = [6.67 x 10^-11 x 6 x 10^24 x m] / (6380000 + h)^2
0.098 = [6.67 x 10^-11 x 6 x 10^24] / (6380000 + h)^2
(6380000 + h)^2 = [6.67 x 10^-11 x 6 x 10^24] / 0.098
(6380000 + h)^2 = 4.08 x 10^15
6380000 + h = 63903626.42
h = 57523626 m
= 57523.63 km

 

[LoneWolf1990]

hey man I really to break it to you but the answers say 1.93x10^5 km. Unless my copy of Dotpoint Physics is stuffed up then that's not it.

 

[Forbidden.]

Finalise your answer with scientific notation.

 

[Mark576]

I got the same answer as namburger. Maybe the answers are wrong?

 

[LoneWolf1990]

Finalise your answer with scientific notation.

how?

 

[namburger]

how?

57523.63 km
5.75 x 10^4 km

 

[LoneWolf1990]

Hey I'm back again with another question I need help with.

Star X is 8.0 ly(light years) from Earth. A spaceship travels at 0.5c to reach the star.

Calculate how long the trip takes as measured by an obsever on Earth.