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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:
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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: • Find height of rocket on several frames • Determine its speed and acceleration • Share and discuss results
Lunar Cratershttp://www.lpi.usra.edu/expmoon/science/craterstructure.html Copernicus Crater d = 93 km Moltke Crater 7 km in diameter Carroll & Ostlie, 1996, Modern Astrophysics
Mars: Ridges in Gordii Dorsum Region http://mars.jpl.nasa.gov/mro/multimedia/images/?ImageID=3263 120 m
Mercury: Crater Machaut http://www.nasa.gov/mission_pages/messenger/multimedia/flyby2_20081007_5.html Larger crater d = 100 km
Scientific Motivation • How do we know these sizes? • No humans have been there • No robots on ground to measure • Remote Sensing: • Measure angles to determine sizes • Colors & spectra surface composition • Texture/reflectivity • Changes over time • Orbiting spacecraft, airplanes, balloons
Mathematical Relation? A = angle (degrees) d = distance (km) s = size (km)
Mathematical Relation! A = angle (degrees) d = distance (km) s = size (km)
Ways to play the eqn: • Know d (radar), measure A, compute s: • Know s (measured), measure A, compute d:
Outline • Scientific Motivation • Today’s Activity: • Measure the height of rocket (d) • Measure size of other objects on ground • Tomorrow’s Activity: • Find height of rocket on several frames • Determine its speed and acceleration • Share and discuss results
Day 1 • Look at video… • Think / plan: • What do we know on the ground (s)? • How do we measure A? • After 5-10 min, then return & share…
Think / plan: • What do we know on the ground (s)? • How do we measure A? 10 ft 25 ft
Measure sizes on computer screen: • object: xo • FOV: xfov
How big is Afov? • Calibrate • Known size (s) at a known distance (d) • Calculate A • Observe video 1 2 3 Afov
Now your turn… • Follow steps (i)-(v) for Day 1 on handout. • Useful Equations:
Outline • Scientific Motivation • Today’s Activity: • Measure the height of rocket (d) • Measure size of other objects on ground • Tomorrow’s Activity: • Find height of rocket on several frames • Determine its speed and acceleration • Share and discuss results
Day 2 • Do some physics: • On one frame, measure d1 • On next frame, measure d2 • Difference: Dd = d2 - d1 • If we know the time between frames, Dt, we can calculate the rocket’s velocity: Dd d2 d1
Day 2 v2 • If you have two velocities: • From d1 and d2, got v1 • From d2 and d3, got v2 • Difference: Dv = v2 - v1 • Calculate the rocket’s acceleration: v1
Now your turn… • Follow steps (i)-(vi) for Day 2 on handout. • Useful Equations:
Last 15 min • Organize your thoughts for class discussion. • Write your results on the board: • Times of observation (frame #s) • Velocities • Accelerations • What did we do right? Wrong? Next time? • What else could we do with videos?