# physics

posted by
**Maria**
.

Using Newton's Law of Universal Gravitation, compare the weight of a 68.1 kg astronaut on the surface of the earth to the gravitational pull of the Earth on the same astronaut when she is on the International Space Station.

Constants: Average altitude of the ISS above the surface of the Earth = 387 km. You can find the other constants you will need on the Astronomy Formula Chart.

(In Moodle, enter large numbers with scientific E notation. Example: 100 = 1.00*102 in scientific notation, or 1.00E2 in scientific E notation. Don't forget measurement units! If there are two blanks, enter the numerical value in the first blank, and the measurement unit in the second blank. Example: 1.0 m + 1.0 m = .)

The weight of the astronaut near the surface of the earth:

Fg = mg = (68.1 kg)(strength of gravitational field, g m/s2) =

The pull of the Earth on the astronaut near the surface of the earth:

(G (Nm2)/kg2)(mass of earth, M♁ )(mass of astronaut, 68.1 kg) / (radius of earth, R♁ m)2 =

The pull of the Earth on the astronaut when she is on the ISS:

(G (Nm2)/kg2)(mass of earth, M♁ )(mass of astronaut, 68.1 kg) / (radius of earth, R♁ m + altitude of ISS: )2 =

So, why is the astronaut 'weightless' when she is on the space station?