Lecture 9: Gravity Practice Flashcards

Vocabulary-style flashcards defining key gravitational concepts, formulas, and constants from Lecture 9.

Apparent weight

The sensation of weight produced by the support force from whatever surface an object is in contact with, which equals the value of that support force.

Weightlessness

A condition experienced during free-fall, such as in orbit, characterized by a zero-support force condition rather than the absence of gravity.

Free-fall

The motion of an object moving only under the influence of gravity with no other forces, including air resistance or support forces, present.

Inverse-square law

A physical principle where a property is proportional to $\frac{1}{d^2}$, meaning that the property's intensity decreases by the square of the distance from the source.

Newton's law of universal gravitation

The equation used to quantify the force of gravity between any two objects: $F = G \frac{m_1 m_2}{d^2}$.

Universal gravitational constant (big G)

The value $6.67 \times 10^{-11} \, \text{Newton meters-squared per kilogram-squared}$ which remains the same anywhere in the universe.

Gravitational acceleration (little g)

The acceleration due to gravity on a celestial body, calculated as $g = G \frac{m}{d^2}$; on Earth's surface, this is approximately $9.8 \, \text{m/s}^2$.

Gravitational field

A model used to describe gravitational interaction where field lines (arrows) indicate the direction of movement toward the center of a massive object.

Theory of general relativity

Einstein's theory explaining the motion of objects as a result of curves in spacetime caused by massive objects.

Spacetime

The fabric of the universe that becomes warped or curved by massive objects, causing other objects to travel in curved paths like orbits.

Support force

The force provided by a surface that opposes gravity; when this force changes due to vertical acceleration, the apparent weight also changes.

Gravitational attraction

A purely attractive force acting between all objects with mass in the universe, which can only be exactly zero if the distance between objects is infinite.