A weather satellite circles Earth. Which force supplies its centripetal force?
The space station, 400 kilometers up, laps Earth in about 93 minutes. A TV satellite 36,000 kilometers up takes a full day for one lap. Lower is faster. A lot faster.
This lesson predicts how a satellite's speed must change when its orbital height changes.
Closer to Earth, the field is stronger: the gravitational force on a low satellite is larger than on a high one.
A larger force bends the satellite's path more sharply toward Earth.
To keep falling around Earth instead of into it, the low satellite's sideways motion must carry it onward faster.
The higher orbit is the mirror case: the force is gentler, the path bends less, and a slower sideways speed keeps the fall missing Earth.
Satellite P orbits lower than satellite Q. Which moves faster along its orbit?
Move a satellite to a lower orbit, and it must speed up to stay in orbit. Move it to a higher orbit, and it must slow down.
Lena says a satellite moved to a higher orbit must speed up to stay in orbit. Is she correct?
The real numbers run the same way: the station at 400 km does about 7.7 kilometers per second (km/s); a navigation satellite at 20,000 km does about 3.9 km/s.
A satellite is moved from a 400 km orbit to a 20,000 km orbit. What must happen to its orbital speed?
Higher up, the gravitational force on the satellite is gentler and bends its path less.
A gentler bend needs a slower sideways speed to keep the fall missing Earth.
Its orbital speed must be lower in the higher orbit.
Two moons circle one planet, one inside the other's orbit. Which moves faster along its orbit?
The inner moon sits where the planet's field is stronger.
A stronger force demands a faster sideways speed to stay in orbit.
The inner moon moves faster.
Esme says a satellite 800 km up moves faster than one 36,000 km up. Is she correct?
Why must a satellite in a low orbit move faster than one in a high orbit?
The table lists three moons of Jupiter and their orbital distances. Which moves fastest along its orbit?
The chart shows two satellites' orbital speeds around Earth. Which satellite orbits closer to Earth?