Physics 20 flashcards ~10 min

Gravitation and Orbital Mechanics

About this deck

From satellites to planetary orbits, gravitation and orbital mechanics explain how objects move through space under gravity's influence, and this deck of 20 flashcards covers the essential formulas and concepts. You'll start with Newton's law of universal gravitation and how gravitational field strength changes with distance, then move into orbital velocity, geostationary orbits, and the concept of escape velocity. The deck covers Kepler's three laws of planetary motion, gravitational potential energy, and the difference between weight and mass in different gravitational fields, along with weightlessness and why astronauts in orbit appear to float. It finishes with practical applications like how GPS satellites work and orbital decay. Suited to A-Level and AP Physics students, this deck connects Newton's foundational equations to the real satellites and orbital mechanics used in modern space technology.

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Every mass attracts every other mass with a force proportional to their masses and inversely proportional to the square of the distance between them.

F = Gm1m2/r²

It decreases with the square of the distance (inverse square law).

The force per unit mass experienced by an object in a gravitational field.

The speed needed for an object to maintain a stable orbit around a larger body.

An orbit where a satellite stays above the same point on Earth, matching Earth's rotation period.

The minimum speed needed for an object to escape a gravitational field without further propulsion.

Planets orbit the Sun in ellipses, with the Sun at one focus.

A line from a planet to the Sun sweeps equal areas in equal times, meaning planets move faster when closer to the Sun.

The square of a planet's orbital period is proportional to the cube of its orbital radius.

The energy an object has due to its position in a gravitational field.

They are in continuous free fall around Earth, so there's no normal force to create the sensation of weight.

Mass is the amount of matter in an object; weight is the gravitational force acting on that mass.

No, mass stays constant; weight changes because gravitational field strength differs.

Gravitational force provides the centripetal force needed for circular motion.

The gradual decrease in a satellite's orbital altitude due to atmospheric drag.

By triangulating signals from multiple satellites with precisely known orbital positions and timing.

An orbit relatively close to Earth's surface, typically used by the ISS and many communication satellites.

Orbital period is time to complete one orbit around another body; rotational period is time to complete one spin on its own axis.

A position in space where the gravitational forces of two bodies balance, allowing an object to remain relatively stable.