Download Speeding Around the Sun

Speeding Around the Sun
Forces acting on the stopper
Tension
of string
Force from hand
Direction of motion
• Why did I need to continue to use a force on the
stopper?
• Gravity pulling down, friction…
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)
gravity
Direction of motion
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 NASA
• Orbits – Orbit demonstration
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
Satellite
Earth
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 NASA