# ? Earth's Gravitational Field Effect on space shuttles

samaank
? Earth's Gravitational Field Effect on space shuttles

Hi, i have a physics question in my physics portfolio, it goes as follows

Critically assess the following statement: ‘Astronauts in a space capsule orbiting the Earth at a height of 900km experience weightlessness: hence the gravitational field due to the Earth must be zero at that altitude'. Include calculations in your answer.

Homework Helper
Do you know the formula for the strength of Earth's gravitational field?

$$F= \frac{GM}{r^2}$$

Where G is the "universal gravitational constant", M is the mass of the earth, and r is the distance from the center of the earth (radius of the Earth plus altitude). For what value of r is that 0?

Whe DO astronauts experience weightlessness? (What weight would you feel if you jumped off the edge of the Grand Canyon?)

samaank
thank you very much, your post made something click in my mind, i got it now. thanks

samaank
HallsofIvy said:
Do you know the formula for the strength of Earth's gravitational field?

$$F= \frac{GM}{r^2}$$

Where G is the "universal gravitational constant", M is the mass of the earth, and r is the distance from the center of the earth (radius of the Earth plus altitude). For what value of r is that 0?

Whe DO astronauts experience weightlessness? (What weight would you feel if you jumped off the edge of the Grand Canyon?)
ok i thought i had it but i didnt, could u please prove that theory mathematically, i tried inputting the numbers but ended up with 610.24234...

Dr.Brain
Astronauts don't feel weightless because of Earth's gravitational field =0 , infact the gravitational field due to Earth is not zero by any means at a height of 900 km. Astronauts would feel weightless if their space-shuttles accelerated in such a way that it counterbalanced the Earth's attraction.Astronauts could feelw eightless if they were under freefall in space , like in case of satellites orbiting earth, in this case Earth's gravitational field helps in motion of satellite and is not zero.Earth's Gravitational field will be zero when r---> infinity.

BJ

samaank
how would i prove that mathematically ?

$$F= \frac{GMm}{r^2}$$