Gravity & Electrostatics

How does the force of gravity between two bodies change when the distance between them is halved?

• The force doubles.

• The force quadruples.

• The force decreases to ¼ of its initial value.

• The force is cut in half.

Why are occupants of the International Space Station weightless?

• The floor of the space station is made from cavorite, which blocks gravity.

• They are in free fall.

• Centripetal force cancels gravity in the space station.

• They are so far from Earth that gravity is essentially zero.

Do tides occur in the Earth's interior?

• Yes, due to the strength of the gravitational force at the center of the core.

• Yes, due to the difference in gravitational force across the core.

• No, due to the difference in gravitational force across the core.

• No, due to the strength of the gravitational force at the center of the core.

Why are all tides greatest at the time of a full Moon or new Moon?

• At full Moon and new Moon, the tides from the Moon and the Sun partially cancel because they are in line with Earth.

• At full Moon and new Moon, the tides from the Moon and the Sun partially cancel because they make a right angle with Earth.

• At full Moon and new Moon, the tides from the Moon and the Sun add because they are in line with Earth.

• At full Moon and new Moon, the tides from the Moon and the Sun add because they make a right angle with Earth.

What would the magnitude of the gravitational field be anywhere inside a hollow, spherical planet?

• Half the surface value

• A quarter of the surface value

• The same as the surface value

• Zero N/kg

Why does gravitation between Earth and the Moon predominate?

• The gravitational force between two protons is billions of times stronger than the electrical force.

• The electrical force gets smaller more quickly with distance than the inverse square gravitational force.

• Gravitational forces grow exponentially with the number of particles, while electrical forces simply add.

• The electric force between Earth and Moon cancels out because they have an equal number of positive and negative charges.

What is a positive ion? What is a negative ion?

• A positive ion is a neutral atom that has gained one or more electrons. A negative ion is a neutral atom that has lost one or more electrons.

• A positive ion is a neutral atom that has lost one or more electrons. A negative ion is a neutral atom that has gained one or more electrons.

• A positive ion is a neutral atom that has lost one or more neutrons. A negative ion is a neutral atom that has gained one or more neutrons.

• A positive ion is a neutral atom that has lost one or more protons. A negative ion is a neutral atom that has gained one or more protons.

What happens to the force between two charges if they are moved to three times the distance?

• The force increases three times.

• The force decreases nine times.

• The force increases nine times.

• The force decreases three times.

Why are metals good conductors of both heat and electricity?

• The outer shell electrons in atoms vibrate in place and emit electromagnetic radiation that travels throughout the metal.

• The outer shell electrons in metals are tightly bound, making it easy for vibrations to move from one atom to the next.

• The outer shell electrons in metals move with zero resistance, making all metals superconductors.

• The outer shell electrons in metals are free to move from atom to atom.

What happens to electrons in any charging process?

• Electrons transfer from one place to another.

• Electrons are created.

• Electrons are destroyed.

• Electrons stay in place as protons are transferred from one place to another.