Chapter 13 Universal Gravitation

Gravitational field

A Gravitational field occupies the space surrounding a massive body. A Gravitational field is an example of a force field,for any mass in the field space experiences a force.

What kind of field surrounds Earth and causes objects to experience gravitational forces?

Earth ca be thought of as being surrounded by a gravitational field that interacts with objects and causes them to experience gravitational forces.

How does the force of gravity change with distance?

Gravity decreases according to the inverse square law. The force of gravity weakens as the square of distance.

What did Newton discover about gravity?

Newton discovered that gravity is universal. Everything pulls on everything else in a way that involves only mass and distance.

What was Newton's reasoning about the apple falling from the tree?

Newton reasoned that the moon is falling toward Earth for the same reason an apple falls from a tree--they are both pulled by Earth's gravity.

What causes ocean tides?

Newton showed that the ocean tides are caused by differences in the gravitational pull of the moon on opposite sides of Earth.

ocean tide

Newton showed that the ocean tides are caused by differences in the gravitational pull of the moon on opposite sides of Earth.

Law of universal gravitation

Newton's law of universal gravitation states that every object attracts every other object with a force that for any two object is directly proportional to the mass of each object.

What theory of the solar system did Newton's theory of gravity confirm?

Newton's theory of gravity confirmed the Copernican theory of the solar system.

What sensation do we interpret as wright?

Pressure against Earth is the sensation we interpret as weight.

How did the formulation of the law of universal gravitation affect science?

The formulation of the law of universal gravitation is one of the major reasons for the success in science that followed, for it provided hope that other phenomena of the world might also be described by equally simple and universal laws.

Describe the gravitational field of Earth at its center.

The gravitational field of Earth at its center is zero.

Why doesn't the moon hit Earth?

The moon is actually falling toward Earth but has great enough tangential velocity to avoid hitting Earth.

Universal Gravitational constant

The universal gravitational constant, G, in the equation for universal gravitation describes the strength of gravity.

What happens to the gravitational field of the a star that has collapsed into a black hole?

When a massive star collapses into a black hole, there is no change in the gravitational field at any point beyond the original radius of the star.

Inverse-square law

When a quantity varies as the inverse square of its distance from its source, it follows an inverse-square law.