Gravity and Astronomy

Most of the Universe is _____

• filled with planets
• filled with stars
• filled with gas and dust
• pretty empty

Gravity from an object _____

• stops at it's surface
• stops after about 10,000 km
• stops at the edge of the solar system
• goes on forever

Isaac Newton got into a bitter feud with _____

• Tycho Brahe
• Robert Hooke
• Galileo Galilei
• Johannes Kepler

You can think of it as "how much stuff makes up an object"

• size
• brightness
• mass
• density

Which term is defined as "how much mass is inside a given volume"?

• size
• brightness
• weight
• density

When the distance from an object is doubled, the force of gravity drops by a factor of _____

• 2
• 4
• 10
• 16

Go 3 times farther away and the force of gravity drops by _____

• 3 times
• 6 times
• 9 times
• 12 times

If there are no other forces acting on them, two objects with mass will _____

• repel
• stay where they are
• move uniformly toward each other
• accelerate toward each other

What can be described as "falling and missing the ground"?

• accelerating
• free-falling
• orbiting
• attaining escape velocity

A rock thrown hard enough sideways will orbit the Earth once every _____

• 9 minutes
• 90 minutes
• 9 hours
• 90 hours