An astronomer observes a planet orbiting a star with a period of 8.7 years and a semimajor axis of 2.7 × 10° km. Find the mass of the star. The universal gravitational constant G = 6.673 × 10-11 m³ kg¬1 s-2.

The International Space Station (ISS) is a space station orbiting the earth above the ground. If the radius of the earth is 3,958.8 miles, mass of earth is 5.972 x 10 24 kg,  the period of the ISS at the orbit around the earth is 9.16 hours, can you calculate what is the distance from the ISS to the surface of the earth, in unit of miles? Use G=6.674 x 10 -11 Nm2/kg2. Write your answer in pure numbers, for example, 4567.8. Please keep at least on digit after the decimal point.

A sphere of copper has a radius of 50.0 cm and a mass of 4690 kg.  A sphere of unknown metal has a radius of 30.0 cm.  The surfaces of the spheres are 20.0 cm apart.  The force of gravitational attraction between the two spheres is 0.372 mN.  What is the mass of the unknown metal?

Assume the earth's mass is 80.004 x 1025 kg, and radius is 35.532 x 103 miles, what would be the gravitational acceleration on such an planet in unit of m/s2? Use G=6.67x 10 -11 Nm2/kg2.

A sphere of copper has a radius of 50.0 cm and a mass of 4690 kg. A sphere of unknown metal has a radius of 30.0 cm. The surfaces of the sphere are 20.0 cm apart. The force of gravitational attraction between the two spheres is 0.372 nM. What is the mass of the unknown metal?

Gravitational force is F = Gm1m2/r². Set G = 1 and m1 = 1, where m2 will be a planet with 1800 times Earth's mass (so m2 = 1800) and 30 times Earth's radius (so r = 30). What will F be?

The ratio of the gravitational field at an altitude 2 RF above the Earth's surface (R = the radius of the Earth) to the field at the Earth's surface is 1/9 1/3 9

The International Space Station (ISS) is a space station orbiting the earth above the ground. If the radius of the earth is 3,958.8 miles, mass of earth is 5.972 x 10 24 kg,  the period of the ISS at the orbit around the earth is 14.137 hours, can you calculate what is the distance from the ISS to the surface of the earth, in unit of miles? Use G=6.674 x 10 -11 Nm2/kg2. Write your answer in pure numbers, for example, 4567.8. Please keep at least on digit after the decimal point.

A satellite m = 500 kg orbits the earth at a distance d = 225km above the of the planetThe radius of the earth r_{e} = 638 * 10 ^ 6 * m and the gravitational constant G = 6.67 * 10 ^ - 11 * N * m ^ 2 / k * g ^ 2 and the Earth's mass m_{e} = 5.98 * 10 ^ 24 * kg What the speed of the satellite in m/s

Astronomical observations of our Milky Way galaxy indicate that it has a mass of about 8 ✕ 1011 solar masses. A star orbiting near the galaxy's periphery is 6.0 ✕ 104 light years from its center. (a) What should the orbital period (in y) of that star be?  y (b) If its period is 6.9 ✕ 107 y instead, what is the mass (in solar masses) of the galaxy? Such calculations are used to imply the existence of "dark matter" in the universe and have indicated, for example, the existence of very massive black holes at the centers of some galaxies.  solar masses