Kepler's Laws
This law states that planets move in elliptical paths with the Sun at one focus.
What is Kepler’s First Law?
The force that keeps planets and satellites in orbit.
What is gravity?
The direction of a satellite’s velocity in circular orbit compared to the gravitational force acting on it.
What is perpendicular?
This happens to the required orbital speed of a satellite as its distance from Earth increases.
What is decrease?
The point in an elliptical orbit where the object is closest to a planet.
What is perigee?
According to Kepler’s Second Law, a planet moves fastest when it is at this point in its orbit.
What is perihelion?
For a satellite in uniform circular orbit, gravity acts as this type of force.
What is centripetal force?
If orbital radius increases, the orbital speed of a satellite does this.
What is decrease?
Escape velocity depends on planetary mass and this quantity.
What is radius of the planet?
In orbital motion, this quantity is conserved even though speed and direction continuously change.
What is angular momentum?
Kepler’s Third Law says that the square of a planet’s orbital period is proportional to this power of its orbital radius.
What is the third power (cube)?
The orbital speed of a satellite depends on mass of the planet and this orbital quantity.
What is orbital radius?
A satellite orbiting very close to Earth compared to one far away will have this kind of orbital period.
What is a shorter orbital period?
Unlike orbital speed, escape velocity does NOT depend on this quantity.
What is the mass of the object leaving the planet?
If the central mass of a star is quadrupled while orbital radius stays the same, orbital speed changes by this factor.
What is 2 times larger?
If Planet A orbits 4 times farther from a star than Planet B, this is how the orbital period changes.
What is 8 times longer?
An astronaut in orbit feels weightless because both the astronaut and spacecraft are accelerating toward Earth at the same rate due to this force.
What is gravity?
The International Space Station stays in orbit because its forward velocity and Earth’s gravity continuously create this type of motion.
What is free fall?
A satellite launched fast enough to continuously go around Earth while falling toward it is said to be in this state.
What is orbit?
Two satellites orbit the same planet; the one with the larger orbital radius has this compared to the one closer in.
What is a longer orbital period?
A newly discovered planet takes 27 Earth years to orbit its star once. Using Kepler’s Third Law compared to Earth, this is the planet’s average orbital radius in AU.
What is 9AU?
A satellite’s orbital radius is increased to 9 times its original value. Compared to its original orbit, its centripetal acceleration changes by this factor.
What is 1/81
A satellite orbits Earth at radius r. Another satellite orbits at radius 16r. Compared to the first satellite, the second satellite’s orbital speed changes by this factor.
What is 1/4?
Compared to a satellite in low Earth orbit, a satellite with a greater orbital radius requires this kind of orbital speed to remain in orbit.
What is lower orbital speed?
A satellite in circular orbit is given a small increase in speed at a single point, causing its path to change from circular to this general type of orbit.
What is an elliptical orbit?