Universal Gravitation

Answer the following questions. Be sure to show all your work. This activity is available below or in a printable version.

Use the diagram to the right and the description below to answer questions 1-5.

Two asteroids with masses m1 and m2 are separated by a distance of 240 meters and feel an attractive force of 820 Newtons.

1. What would the force between the asteroids be if the distance were cut in half, to 120 meters?

a. 205 N

b. 410 N

c. 820 N

d. 1,640 N

e. 3280 N

2. What would the force be between the asteroids if m₂ were doubled?

a. 410 N

b. 820 N

c. 1,230 N

d. 1640 N

e. 3,280 N

3. What would the force be between the asteroids if m₁ were decreased to 1/3 its original value?

a. 91.1 N

b. 273 N

c. 410 N

d. 1640 N

e. 2460 N

4. At what distance would the force be decreased to 32.8 N?

a. 9.6 m

b. 48 m

c. 480 m

d. 1,200 m

e. 6000 m

5. What is the gravitational force on a 1 kg mass on the surface of Pluto, which has a mass of 1.32 x 10²² kg and a radius of 1.15 x 10⁶ m? Show your work.

6. Mars’ moon Phobos has a mass of about 9.6 x 10¹⁵ kg and its orbit is 9.4 × 10⁶ m above the center of Mars. If the mass of Mars is 6.4 × 10²³ kg, what is the magnitude of the gravitational force between the two bodies?

7. In addition to Phobos, a moon called Deimos also orbits Mars. Deimos orbits with an average speed of 1.35 km/s, while Phobos orbits at an average speed of 2.14 km/s. Which of the two moons is in a higher orbit above Mars? Support your answer.

Once you have finished answering the questions, submit your responses to the dropbox.