Question

part a: how does the author’s discussion of the relationship between momentum and gravity contribute to an understanding of orbits?
a. the author shows how orbits are possible by explaining that gravity has to offset an object’s momentum in order for the object to stay in orbit.
b. the author emphasizes how orbits can become unstable over time if a satellite’s gravity becomes too strong.
c. the author proves that an object’s gravity is more important for keeping a satellite in orbit than its momentum.
d. the author emphasizes how satellites can become dangerous to the objects they orbit if their momentum is too strong.

1. part b: which line from the text best supports the answer to part a?

a. “an object in motion will stay in motion unless something pushes or pulls on it.” (paragraph 5)
b. “without gravity, an earth - orbiting satellite would go off into space along a straight line.” (paragraph 5)
c. “an object’s momentum and the force of gravity have to be balanced for an orbit to happen.” (paragraph 6)
d. “if momentum is too small, the object will be pulled down and crash.” (paragraph 6)

Explanation:

To answer Part B, we need to find which line from the text supports the answer to Part A. Part A asks how gravity contributes to an understanding of orbits. The key idea is that gravity and momentum need to be balanced.

• Option A: Talks about an object in motion staying in motion unless pushed/pulled. This is more about Newton's first law (inertia) rather than the balance of gravity and momentum for orbits.
• Option B: Mentions a satellite going off into space without gravity. This shows the role of gravity (as a pull), but doesn't address the balance with momentum.
• Option C: States that an object's momentum and the force of gravity have to be balanced for an orbit. This directly addresses the relationship between gravity and momentum for orbits (which is what Part A is about - how gravity contributes, through this balance).
• Option D: Discusses what happens if momentum is too small (object crashes). While it involves momentum, it doesn't highlight the balance with gravity as comprehensively as Option C.

Answer:

C. "An object's momentum and the force of gravity have to be balanced for an orbit to happen." (Paragraph 6)