8th Grade Science Review 15 (Gravity)

Which of the following planets takes the longest time to complete one revolution of the sun?
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• Earth
• Venus
• Mercury
• Jupiter

Which of the following statements about the gases in Earth’s atmosphere is true?

• The gases in the atmosphere are nonreactive.
• Most of the ozone in the atmosphere is located in the photosphere.
• 78% of Earth’s atmosphere is nitrogen, 21% is oxygen, and the rest is other gases.
• Oxygen was one of the gases in Earth’s very early atmosphere.

A student swings a ball attached to a string to model the moon’s orbit around the Earth. What force does the string represent?

• inertia
• pressure
• gravity
• momentum

If there were no gravitational forces acting on the moon, the moon would

• quickly crash into the Earth.
• continue at a constant speed in a straight line through space.
• still orbit Earth as it does now.
  
• remain stationary, at a fixed distance from Earth.

Why don’t you notice the gravitational pull of objects towards you or your body towards objects, such as a pencil?

• The force of gravity influences only objects that are very close together.
• You don’t notice the pull because Earth’s pull is greater.
  
• Small objects exert no gravitational force.
  
• The mass is too small to ca use a force large enough to notice.

Which of the following statements explains the Law of Universal Gravitation?

• Objectsintheuniverseattracteachotherthroughgravitationalforce, depending on their weights and the distance between them.
• Objectsintheuniverseattracteachotherthroughfrictionalforce,based on friction and the distance of their masses.
• Objects in the universe attract each other through gravitational force, depending on their masses and distance between the objects.
• Objectsintheuniverseattracteachotherthroughmotivationalforces, depending on their weights and masses.

What is the measure of gravitational force on an object?

• friction
• weight
• balance
• mass

How does mass affect gravitational force?

• Gravitational force decreases as the masses of the objects increase.
• Gravitational force increases as the masses of the objects increase.
• Gravitational force increases as the masses of the objects decrease.
• Gravitational force between objects does not dependon their masses.

What force prevents the moon from moving away from Earth?

• tides
• inertia
• electromagnetism
• gravity