I really do not understand Number 7

Which of these does Newton's law of universal gravitation imply?
(Points : 1)
The force of gravity between two objects is inversely proportional to the product of the two masses. <--

Earth's gravity acts on people inside a space station orbiting the earth.

Gravity increases with distance from a planet.

What goes up must come down.

Question 2. 2. What is "universal" about Newton's law of universal gravitation?
(Points : 1)
It predicts the same force of attraction independent of the distance between the objects.

It describes gravitational forces on earth, which is part of the universe. <--

The mathematical expression has the same form in any language.

It applies to any two objects at any location.

Question 3. 3. A 60.0 kg student is standing on the pavement outside. To use Newton's law of universal gravitation to find the weight of the student, you should calculate the weight as the force of attraction between the student and what?
(Points : 1)
the pavement

the entire earth, located one earth radius away <--

the entire earth, located at a distance equal to the student's height

the part of the mass of the earth that is near the student

Question 4. 4. A satellite is in geosynchronous orbit around earth, so that it stays above the same point on earth and has a period of exactly one day. Another satellite orbits earth at a distance twice as far from earth's center. What is the period of the second satellite? Assume the radius of earth is 6,378 km and the mass of each satellite is 200 kg.
(Points : 1)
0.13 day

0.35 day

2.8 days <--

4 days

8 days

Question 5. 5. An astronaut weighs 800 N on the surface of earth. What is the weight of the astronaut 6.37 × 106 m above the surface of the earth? Assume the radius of earth is 6,378 km.
(Points : 1)
0.0 N

200 N <--

1,600 N

3,200 N

Question 6. 6. The centers of two 15.0 kg spheres are separated by 3.00 m. The magnitude of the gravitational force between the two spheres is approximately what?
(Points : 1)
1.11 × 1010 N

3.34 × 1010 N

1.67 × 109 N <--

5.00 × 109 N

Question 7. 7. Use Newton's law of universal gravitation to find the speed of the International Space Station in its orbit at an elevation of 350 km. Earth's radius is 6,378 km, earth's mass is 5.98 × 1024 kg, and the mass of the International Space Station is 304,000 kg.
(Points : 1)
7.70 km/s

7.91 km/s <--

4,300 km/s

4,300 m/s

1.7 × 106 m/s

6 answers

1) b
2)d
3)correct
4)correct
5)correct
6)correct
7)a
Which of these does Newton's law of universal gravitation imply?
(Points : 1)
The force of gravity between two objects is inversely proportional to the product of the two masses. <--
NO!!!!!!!!!! DIRECTLY PROPORTIONAL
+++++++++++++++++++++++++++
Earth's gravity acts on people inside a space station orbiting the earth.
YES !!!!!!!!!!!!!!!!!
**********************************
Gravity increases with distance from a planet.

What goes up must come down.

Question 2. 2. What is "universal" about Newton's law of universal gravitation?
(Points : 1)
It predicts the same force of attraction independent of the distance between the objects.

It describes gravitational forces on earth, which is part of the universe. <--
NO !!!!!!!!!!!!!~!!~!!

The mathematical expression has the same form in any language.
******************************
It applies to any two objects at any location.
YES !!!!!!!!
********************************

Question 3. 3. A 60.0 kg student is standing on the pavement outside. To use Newton's law of universal gravitation to find the weight of the student, you should calculate the weight as the force of attraction between the student and what?
(Points : 1)
the pavement

the entire earth, located one earth radius away <--
YES !!!!!!!

the entire earth, located at a distance equal to the student's height

the part of the mass of the earth that is near the student

Question 4. 4. A satellite is in geosynchronous orbit around earth, so that it stays above the same point on earth and has a period of exactly one day. Another satellite orbits earth at a distance twice as far from earth's center. What is the period of the second satellite? Assume the radius of earth is 6,378 km and the mass of each satellite is 200 kg.
*****************************
Kepler # 3
T^2/R^3 = constant
so
1^2/R1^3 = T^2/(2R1)^3
T^2 = 8
T = 2.83 days
***************************
(Points : 1)
0.13 day

0.35 day

2.8 days <-- YES

4 days

8 days

Question 5. 5. An astronaut weighs 800 N on the surface of earth. What is the weight of the astronaut 6.37 × 106 m above the surface of the earth? Assume the radius of earth is 6,378 km.
(Points : 1)
***********************************
R earth = 6.378*10^6 meters
Rastronaut = (6.37+6.378)10^6 = about 2 R
double R--> 1/4 force
*************************
0.0 N

200 N <-- YES

1,600 N

3,200 N

Question 6. 6. The centers of two 15.0 kg spheres are separated by 3.00 m. The magnitude of the gravitational force between the two spheres is approximately what?
******************************
F = 6.67*10^-11 (15)(15)/9 = 167*10^-11
= 1.67*10^-9
***********************************
(Points : 1)
1.11 × 1010 N

3.34 × 1010 N

1.67 × 109 N <-- TYPO 10^-9 but yes

5.00 × 109 N

Question 7. 7. Use Newton's law of universal gravitation to find the speed of the International Space Station in its orbit at an elevation of 350 km. Earth's radius is 6,378 km, earth's mass is 5.98 × 1024 kg, and the mass of the International Space Station is 304,000 kg.
(Points : 1)
*********************************
r = 6.378*10^6 + .350*10^6 = 6.73*10^6 meters

F = m a = m v^2/r
G m M/r^2 = m v^2/r
G M /r = v^2
6.7*10^-11 (6*10^24)/6.73*10^6
v^2 = 5.97 * 10^7 = about 60*10^6
so
v = 7.73 * 10^3 m/s
= 7.73 km/s
so NO

7.70 km/s <<<<<<<--------I get this

7.91 km/s <-- I disagree

4,300 km/s

4,300 m/s

1.7 × 106 m/s

Answer this Question
1) Earth's gravity acts on people inside a space station orbiting the earth.
2) It applies to any two objects at any location.
3) the entire earth, located one earth radius away
4) 2.8 days
5) 200 N
6) 1.67 x 10^-9 N
7) 7.70 km/s

I just took this quiz. These are the answers.
Which of these does newtons law of universal gravitation imply?
Correct - earth gravity acts on people inside...

What is universal about Newtons law of universal gravitation?
Correct- it applies to any two objects at any location.

I thought the quiz with Damon's answers and got theses wrong but what I am giving you is right.
The Answer to question 7 is, 7.70 km/s. I took the test.
The answer to #7 is 7.70 km/s. I took the test aswell