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Remote Sensing Activity : Physics from a Rocket-Borne Video Camera. Andrew Layden BGSU. ACTION Summer Bridge Program. July 22, 2010. Outline. Scientific Motivation Today’s Activity: Measure the height of rocket Measure size of other objects on ground Tomorrow’s Activity: - PowerPoint PPT Presentation
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Remote Sensing ActivityRemote Sensing Activity::
Physics from a Rocket-Borne Physics from a Rocket-Borne Video CameraVideo Camera
Andrew LaydenAndrew LaydenBGSUBGSU
ACTION Summer Bridge Program July 22, 2010
OutlineOutline
• Scientific MotivationScientific Motivation• Today’s Activity:Today’s Activity:
• Measure the height of rocketMeasure the height of rocket• Measure size of other objects on groundMeasure size of other objects on ground
• Tomorrow’s Activity:Tomorrow’s Activity:• Find height of rocket on several framesFind height of rocket on several frames• Determine its speed and accelerationDetermine its speed and acceleration
• Share and discuss resultsShare and discuss results
Lunar CratersLunar Cratershttp://www.lpi.usra.edu/expmoon/science/craterstructure.htmlhttp://www.lpi.usra.edu/expmoon/science/craterstructure.html
Carroll & Ostlie, 1996, Modern Astrophysics
Moltke Crater7 km in diameter
Copernicus Craterd = 93 km
Mars: Ridges in Gordii Dorsum RegionMars: Ridges in Gordii Dorsum Region
Mars: Ridges in Gordii Dorsum RegionMars: Ridges in Gordii Dorsum Regionhttp://mars.jpl.nasa.gov/mro/multimedia/images/?ImageID=3263http://mars.jpl.nasa.gov/mro/multimedia/images/?ImageID=3263
120 m
Mercury: Crater MachautMercury: Crater Machauthttp://www.nasa.gov/mission_pages/messenger/multimedia/flyby2_20081007_5.htmlhttp://www.nasa.gov/mission_pages/messenger/multimedia/flyby2_20081007_5.html
Larger craterd = 100 km
Scientific MotivationScientific Motivation• How do we know these sizes?How do we know these sizes?
• No humans have been thereNo humans have been there• No robots on ground to measureNo robots on ground to measure
• Remote Sensing:Remote Sensing:• Measure angles to determine sizesMeasure angles to determine sizes• Colors & spectra Colors & spectra surface composition surface composition• Texture/reflectivityTexture/reflectivity• Changes over timeChanges over time
• Orbiting spacecraft, airplanes, balloons Orbiting spacecraft, airplanes, balloons
AA = angle (degrees) = angle (degrees)
dd = distance (km) = distance (km)
ss = size (km) = size (km)
Mathematical Mathematical Relation?Relation?
AA = angle (degrees) = angle (degrees)
dd = distance (km) = distance (km)
ss = size (km) = size (km)
Mathematical Mathematical Relation!Relation!
€
tanA =s
d
• Know Know dd (radar), (radar), measure measure AA, , compute compute ss::
• Know Know ss (measured), (measured), measure measure AA, , compute compute dd::
Ways to play Ways to play the eqn:the eqn:
€
s = d tanA
€
d =s
tanA
OutlineOutline
• Scientific MotivationScientific Motivation• Today’s Activity:Today’s Activity:
• Measure the height of rocket (Measure the height of rocket (dd))• Measure Measure ssize of other objects on groundize of other objects on ground
• Tomorrow’s Activity:Tomorrow’s Activity:• Find height of rocket on several framesFind height of rocket on several frames
• Determine its speed and accelerationDetermine its speed and acceleration
• Share and discuss resultsShare and discuss results
Day 1Day 1
• Look at video…Look at video…
• Think / plan:Think / plan:• What do we know on the ground (What do we know on the ground (ss)?)?
• How do we measure How do we measure AA? ?
• After 5-10 min, then return & share…After 5-10 min, then return & share…€
d =s
tanA
• Think / plan:Think / plan:• What do we know on the ground (What do we know on the ground (ss)?)?
• How do we measure How do we measure AA? ?
€
d =s
tanA
Measure sizes on computer screen:
• object: xo
• FOV: xfov
Make a proportion:
€
AoA fov
=xox fov
Solve for Ao:
€
Ao = A fovxox fov
How big is How big is AAfovfov??
• CalibrateCalibrate• Known size (Known size (ss) at a known distance () at a known distance (dd))• Calculate Calculate AA
• Observe videoObserve video 1 2 3
Now your turn…Now your turn…
• Follow steps (i)-(v) for Day 1 on handout.Follow steps (i)-(v) for Day 1 on handout.
• Useful Equations:Useful Equations:
€
tanA =s
d
€
Ao = A fovxox fov
OutlineOutline• Scientific MotivationScientific Motivation• Today’s Activity:Today’s Activity:
• Measure the height of rocket (Measure the height of rocket (dd))• Measure Measure ssize of other objects on groundize of other objects on ground
• Tomorrow’s Activity:Tomorrow’s Activity:• Find height of rocket on several framesFind height of rocket on several frames
• Determine its speed and accelerationDetermine its speed and acceleration
• Share and discuss resultsShare and discuss results
Day 2Day 2
• Do some physics:Do some physics:• On one frame, measure On one frame, measure dd11
• On next frame, measure On next frame, measure dd22
• Difference: Difference: dd = = dd22 - - dd11
• If we know the time between If we know the time between frames, frames, tt, we can calculate , we can calculate the rocket’s velocity:the rocket’s velocity:
€
v =Δd
Δt
d1
d2
d
Day 2Day 2
• If you have two velocities:If you have two velocities:• From From dd1 1 and and dd22, got , got vv11
• From From dd22 and and dd33, got , got vv22
• Difference: Difference: vv = = vv22 - - vv11
• Calculate the rocket’s Calculate the rocket’s acceleration:acceleration:
€
a =Δv
Δt
v1
v2
Now your turn…Now your turn…
• Follow steps (i)-(vi) for Day 2 on handout.Follow steps (i)-(vi) for Day 2 on handout.
• Useful Equations:Useful Equations:
€
tanA =s
d
€
Ao = A fovxox fov
€
v =Δd
Δt
€
a =Δv
Δt
Last 15 minLast 15 min
• Organize your thoughts for class Organize your thoughts for class discussion.discussion.
• Write your results on the board: Write your results on the board: • Times of observation (frame #s)Times of observation (frame #s)• VelocitiesVelocities• AccelerationsAccelerations
• What did we do right? Wrong? Next time?What did we do right? Wrong? Next time?• What else could we do with videos?What else could we do with videos?
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