Speeding Around the Sun

Forces acting on the stopper Why did I need to continue to use a force on the stopper? Gravity pulling down, friction… Direction of motion Tension of string Force from hand

Reflection Questions If string let go  stopper would fly out like marble did with the tape Yes stopper is accelerating  changing directions! Earth (stopper), Sun (straw-Mrs. O’s hand) Direction of motion gravity Direction planet would move without the sun’s gravitational pull. This motion is due to the planet’s inertia.

Data Trend Times increased as the length of string increased. Orbital speed should decrease as string length increased. Reasons this might not have happened: –Timing and counting issues –Inconsistency of the force used when swinging the stopper –The string getting tangled with the straw and or finger

Why did this happen? Farther away from hand – less tension on the string (force) Less force then less acceleration – changes directions slower –For planets – farther away from sun, less gravity – less acceleration

Why did this happen continued… Energy! Farther from hand (the sun) the more potential energy the object has. The more potential energy then less kinetic energy Less kinetic energy, less speed! Think of a roller coaster or the homework assignment on comets, orbit and energy

Planet speed Planets closest to sun are the fastest Planets farthest from sun are the slowest

What is a Satellite? Satellite: an object that orbits another object in space Natural: planets and moons Artificial: Man made

Why are satellites used? Communication Military Weather To study and take pictures of the Earth GPS

Launching a Satellite Launched with a rocket, generally satellite launch – videos from NASAsatellite launch Orbits – Orbit demonstrationOrbits

Just in Case You Wanted to Know… Rocket goes straight up with satellite and then tilts normally towards the East so Earth’s rotation can give it a boost When satellite is horizontal the satellite is released from launch vehicle

Earth Satellite Gravitational Force (the centripetal force) Inertia: Forward Motion Satellite is falling around the curved Earth

Fuel Satellites only need fuel in orbit to run instruments, overcome drag due to air resistance (friction), to reposition… The higher the altitude the longer it can stay in orbit (less air resistance) Types of fuels – solar panels, batteries, fuel cells, nuclear (for missions going to other planets), ion propulsion…

Speed If satellite is closer to Earth its orbital speed will be faster – just like planets that are closer to the sun

Just in Case You Wanted to Know If satellite is 150 miles high – 17,000 mph If 22,223 miles high – 7,000 mph –this type of satellite revolve around the Earth once for every rotation of Earth – called Geosynchronous orbit – hover over 1 point of Earth

To Leave Orbit Satellite should speed up to escape Earth’s gravity (need to be going at least 25,000 mph!) If satellites slow down they will eventually come back down to Earth (will crash or burn up)

Orbiting Another Planet If satellite goes by another planet at a close enough distance and a specific speed the satellite will be pulled in by the planet’s gravity and will begin to orbit that planet Probably will be different speeds/distances then when orbiting Earth Mars Orbiter – videos from NASAMars Orbiter