Question

figure 1 size comparison between io (lower left), the moon (upper left) and earth. credit: nasa/jpl/university of arizona
which two of the following observations provide evidence that io has a stronger gravitational pull than earth’s moon?
a. io has a larger diameter than earth’s moon.
b. volcanic eruptions on io can eject material to greater heights.
c. io’s orbit around jupiter is faster than the moon’s orbit around earth.
d. an astronaut would weigh more standing on io’s surface than on earth’s moon.
e. io has a higher surface temperature than earth’s moon.

Explanation:

To determine which observations show Io has a stronger gravitational pull than Earth’s Moon, we analyze each option:

• Option A: Gravitational pull depends on mass (and radius). A larger diameter (implying larger radius, if density is similar) suggests more mass, so stronger gravity.
• Option B: Ejecting material to greater heights would be easier with weaker gravity (less pull to hold material down). So this suggests weaker gravity, not stronger.
• Option C: Orbital speed depends on the central body (Jupiter vs. Earth) and orbital radius, not Io/Moon’s gravity. Irrelevant.
• Option D: Weight is \( F_g = mg \); more weight on Io means \( g \) (surface gravity) is higher, so stronger gravitational pull.
• Option E: Surface temperature relates to heat sources (e.g., tidal heating for Io), not gravity. Irrelevant.

Answer:

A. Io has a larger diameter than Earth's moon, D. An astronaut would weigh more standing on Io's surface than on Earth's moon