Physics 205A Quiz 4, fall semester 2013
Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problems 7.18, 7.20
The Space Shuttle (mass 94,000 kg) and the International Space Station (mass 370,000 kg) are docked together, and use springs to push off against each other to separate while undocking.[*] Ignore friction/drag, external forces, and consider the Space Shuttle and International Space Station as having zero velocity prior to undocking. The __________ undergoes a greater magnitude momentum change from the undocking procedure.
(A) Space Shuttle.
(B) International Space Station.
(C) (There is a tie.)
(D) (Not enough information is given.)
[*] "Space Shuttle Orbital Docking System," http://www.nasa.gov/pdf/593864main_AP_ED_Phys_ShuttleODS.pdf.
Correct answer (highlight to unhide): (C)
Neglecting external impulses to the Space Shuttle/International Space Station system, then their total momentum is conserved:
0 = ∆pshuttle + ∆pstation.
This means that the change in the Space Shuttle's momentum must then be equal in magnitude (and opposite in sign) to the change in the International Space Station's momentum change:
-∆pshuttle = ∆pstation.
(Note that due to its smaller mass, the Space Shuttle would have a greater final speed than the International Space Station:
-mshuttle·(vshuttle,f - vshuttle,i) = mstation·(vstation,f - vstation,i),
where the initial velocities of the Space Shuttle and the International Space Station are both zero:
-mshuttle·(vshuttle,f - 0) = mstation·(vstation,f - 0),
-mshuttle·vshuttle,f = mstation·vstation,f,
vshuttle,f = -(mstation/mshuttle)·vstation,f.
However, their final momenta would have the same magnitude (and be in opposite directions).)
Sections 70854, 70855, 73320
Exam code: quiz04iSs5
(A) : 34 students
(B) : 8 students
(C) : 24 students
(D) : 0 students
Success level: 36%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.79
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