Gravity and Scale Model

The factor(s) that most affect the gravitational force between two objects are^[i]:

[i] Adapted from E.E. Prather’s assessment.

• size and distance
• mass and size
• density and distance
• mass and distance

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NGSS.MS-PS2-2

NGSS.MS-PS2-4

Planets A, B and C are identical. A and C have a giant moon orbiting them, while B has a   lightweight artificial satellite orbiting it, as shown in the diagram. Which planet has the strongest   gravitational interaction with its satellite?

• Planet A, because its moon is heavy and close to it.
• Planet B, because only a lightweight object can orbit without falling down. 
• Planet C, because it can interact with a heavy object that is far away.
• All have the same gravitational attraction, because the planets are all the same mass.

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NGSS.MS-ESS1-2

NGSS.MS-PS2-4

Why doesn’t the gravitational pull between the Sun and the planets cause the planets to fall into the   Sun?

• The background stars pull back on the planets. 
• The Sun’s magnetic fields are pushing out.
• The speed of the planets flings them out. 
• The Sun’s rotation pushes the planets out. 

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NGSS.MS-ESS1-2

NGSS.MS-PS2-4

Satellites B is three times more massive than A, but orbiting the planet at three times the distance.   Compare the force of gravity between each satellite and the planet. The diagram is not to scale.

• A experiences a stronger force than B, because   differences in distance are more influential than   differences in mass.
• B experiences a stronger force than A, because   differences in mass are more influential than      differences in distance. 
• A and B experience the same force, because differences   in distance are exactly compensated     by differences in mass. 
• A and B experience no force, because they are in space.

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NGSS.MS-ESS1-2

NGSS.MS-PS2-4

Assuming the Earth is perfectly round and each person is the same   mass, which person standing on Earth’s surface experiences a   stronger force of gravity? 

• Both A and D, they are near a stronger magnetic field.
• B, he is affected by both the magnetic field and the rotation.
• D, he is at the bottom of Earth and could fall off.
• All the same, they are the same distance from Earth’s center.

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NGSS.MS-PS2-4

NGSS.MS-PS2-5

Why does the Earth exert a gravitational force on objects on its surface?

• It has an atmosphere.
• It is very dense.
• It has a magnetic field.
• It has mass.

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NGSS.MS-PS2-4

Suppose the Sun shrank in size but its mass remained the same so that it was compacted much   more densely. What would happen to the size of the Earth’s orbit around the Sun^[i]?

[i] Adapted from a question by Philip Blanco.

• Earth's orbit would get smaller.
• Earth's orbit would get larger.
• Earth would fly out of the solar system.
• Earth's orbit would be unaffected.

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NGSS.MS-ESS1-2

NGSS.MS-PS2-4

The gravitational force between two objects is zero^[i] …

[i] Adapted from E.E. Prather’s assessment.

• when another object lies in-between the two original objects.
• when the distance between them becomes extremely large.
• at a location halfway between the two objects.
• when the two objects are not moving. 

This diagram shows two smaller planets of mass m and one larger planet of mass 4 m, aligned and separated by distance d between each planet.  Planet A experiences a gravitational force by Planet C that is ­­­­­­­­­­­______ that by Planet B.

• less than
• equal to
• greater than
• It cannot be determined.

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NGSS.MS-PS2-4

This diagram shows two smaller planets of mass m and one larger planet of mass 4 m, aligned and separated by distance d between each planet.  Which one of the following gravitational forces is strongest?

• The force by Planet A on Planet B.
• The force by Planet A on Planet C.
• The force by Planet B on Planet C.
• The force by Planet C on Planet A.

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NGSS.MS-PS2-4

NGSS.MS-PS2-5