All Flashcards
What are the key differences between circular and elliptical orbits?
Circular: Constant speed, gravitational force always perpendicular to velocity. | Elliptical: Varying speed, gravitational force not always perpendicular to velocity.
Compare and contrast Kepler's First and Second Laws.
First Law: Describes the shape of the orbit (ellipse). | Second Law: Describes the speed of the planet at different points in the orbit (equal areas in equal times).
What is the effect of increasing the mass of a central body on the orbital velocity of a satellite?
The orbital velocity of the satellite increases.
What is the effect of increasing the radius of an orbit on the orbital period?
The orbital period increases.
What is the effect of a spacecraft passing close to a planet during a gravity assist?
The spacecraft's speed and/or direction changes due to the interaction with the planet's gravitational field.
What happens if a satellite's initial velocity is too slow?
The satellite falls inward towards the central body.
What happens if a satellite's initial velocity is too fast?
The satellite may escape the orbit.
Define Newton's Law of Universal Gravitation.
Every particle attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers: F = G rac{m_1 m_2}{r^2}
What is a circular orbit?
An orbit where an object moves in a circle around another object, with constant speed and gravitational force always perpendicular to the velocity.
What is an elliptical orbit?
An orbit where an object moves in an ellipse around another object, with varying speed and gravitational force not always perpendicular to the velocity.
Define orbital velocity.
The velocity required for an object to maintain a stable orbit around a central body:
What is orbital period?
The time it takes for an object to complete one full orbit around another object:
Define semi-major axis.
Half of the longest diameter of an ellipse. It is used in Kepler's Third Law to relate orbital period and orbital size.
What is a geostationary orbit?
A circular orbit above the equator with an orbital period equal to the rotation period of the central body, making the satellite appear stationary from the ground.