Download Physics Section 7.3 Apply Kepler*s Laws of Planetary

Physics Section 7.3
Apply Kepler’s Laws of Planetary Motion
The Polish astronomer Nicolas Copernicus was the first to
correctly place the sun at the center of our solar system.
Johannes Kepler perfected the Copernicus model by
devising three laws of planetary motion.
1st Law: Each planet
travels in an elliptical
orbit around the sun
and the sun is at one
of the focal points
2nd Law: An imaginary
line drawn from the sun
to the planet sweeps
out equal areas in equal
times.
3rd Law: The square of the planet’s orbital period (one
year) is proportional to the cube of the average distance
between the planet and the sun.
T2 =
or
T=
and
vt =
Gm
r
T = period (s)
m = mass of star(object
being orbited) (kg)
r = average distance from
planet to sun
G = 6.67 x 10-11 N m2/kg2
example
A large planet orbiting a distant star is discovered.
The planet’s orbital distance is 7.5 x 1010 m, and its
period is 105.5 days. Calculate the mass of the star
and the planets orbital speed.
example
A satellite is to orbit above the Earth at an altitude of
350 km. Find the velocity required to maintain a
circular orbit. What is the period of the orbit?
assignment
page 253
Problems 1,2,5,6,7