http://www.ck12.org Chapter 6. Universal Gravitation
s/chapter11section4.rhtml
- What are some of the things the astronauts are learning to do/practicing in this video?
- These astronauts are in a plane, flying over Earth. How do they simulate weightlessness?
- How is a falling elevator similar to an orbiting satellite?
- Why does your weight double when the elevator is rising with an acceleration ofg?
- Why doesn’t the pen fall when you drop it while weightless?
Review
Questions
- Sally’s mass on the earth is 50. kg.
(a) What is her weight on the earth?
(b) What is her weight on the moon?
(c) What is her mass on the moon? - The radius of the planet Mercury is 2.43× 106 m and its mass is 3.2× 1023 kg.
(a) Find the speed of a satellite in orbit 265,000 m above the surface.
(b) Find the period of the satellite. - A geosynchronous orbit is an orbit in which the satellite remains over the same spot on the earth as the earth
turns. This is accomplished by matching the velocity of the satellite to the velocity of the turning earth. The
orbital radius of a geosynchronous satellite is 4.23× 107 m (measured from the center of the earth).
(a) What is the speed of the satellite in orbit?
(b) What is its period?
Kepler described the motion of the planets back in the 17thcentury, but it wasn’t until Isaac Newton created his Law
of Universal Gravitation that we had a solid explanation of the reason for planetary motion. This chapter explained
Kepler’s Laws of Planetary Motion and the fact that all objects, regardless of size or distance, exert a gravitational
pull on each other. Incorporating the lessons of circular motion from earlier, we explored satellite orbits and the
sensation of weightlessness in space.